Is this an approved medicine or something bought online?

Approved, and it has been for a long time. It was first cleared in the US in 1978, and it is on sale in Sweden and across the EU through national approvals, including Minirin. It comes as a tablet, a tablet that melts in the mouth or under the tongue, a nose spray and an injection. Which one is used depends on what it is being used for.

Why does it have a warning in a black box on the label?

Because it can push blood sodium low enough to be dangerous. The wording is that severe low sodium can be life-threatening, and can lead to fits, coma, stopped breathing or death. That is why the label rules the drug out for whole groups of people, and sets blood tests at seven days and about a month after starting.

How much difference does it actually make to getting up at night?

Not much, on average. The larger of the two nasal-spray trials ran 12 weeks in 612 adults. The higher spray strength averaged 1.5 fewer trips a night against 1.2 fewer on a dummy spray, a difference of about a third of one trip. What separates the groups more clearly is how many people halved their trips: 47% against 27%. The second trial, in 433 adults, came out close to the same.

Does it cure bedwetting, or only hold it off?

It holds it off. The 2025 Cochrane review of 95 trials in 8,473 children found roughly 1.8 fewer wet nights a week than a dummy tablet while the treatment was being taken. It also found about three times the chance of reaching 14 dry nights in a row. What was measured is the benefit during treatment. Compared with desmopressin, a bedwetting alarm may leave more children dry at follow-up, once treatment has ended.

If it helps a bleed once, will it help again the next day?

Less well. It works by emptying a store of clotting proteins held in the lining of blood vessels, and the store takes time to refill. In a 2024 Dutch study of people having an operation, the second day's rise was 42.9% of the first day's in 17 people, and the third day's was 36.4% in 11. The product information puts the same point as a rule of thumb: doses repeated more often than every 48 hours work less well.

Why is it banned in sport if it does not build muscle?

Because it hides other doping. Keeping water in the body dilutes the blood. The diluted sample gives lower readings for the packed red cell fraction, haemoglobin and the OFF-hr score, which are the figures used to detect blood doping. The World Anti-Doping Agency lists it under diuretics and masking agents on the 2026 Prohibited List, banned at all times, in and out of competition.

Therapeutic

Desmopressin (DDAVP)

Also known as DDAVP · Minirin · Octostim · Nocutil

Approved medicine

21 of 51 peptides sit at this level

Category: Therapeutic
Doping status: Banned in sport
Sources: 14

Desmopressin is a laboratory-made copy of vasopressin, the hormone that tells the kidney to hold on to water. It has been a prescription medicine since 1978. It is used for a body that cannot concentrate its urine, for bedwetting in children, and for lifting clotting proteins for a few hours in two inherited bleeding disorders. What it does inside the body is well measured and not disputed; the argument is about how much good it does, set against one danger. Holding water in the body thins the sodium in the blood, and severe cases of that have caused fits and deaths. It is also banned in sport at all times, because diluting the blood hides blood doping.

Desmopressin (DDAVP)What it is

What it is
Sold and legal
In your body
What changed
What can go wrong
Amounts studied
What people say
Unknowns
Questions
Sources

What it is

A synthetic version of vasopressin, the body's own water-retaining hormone, in clinical use since the 1970s. The US product information gives the chemical name 1-(3-mercaptopropionic acid)-8-D-arginine-vasopressin: position 1 is missing an amino group and position 8 contains a mirror-image arginine, which means the molecule cannot be written correctly in the standard one-letter code.

How it is sold, and whether it is legal

Sold as: As a tablet or melt-in-the-mouth tablet, as a nasal spray, or by injection, depending on the product and what it is being used for.
Legal status in the EU: An approved prescription medicine in Sweden and the EU through national approvals. ATC code H01BA02 in the WHO index, with several brands and formulations.

What it does in your body

5 parts of the body · 4 measured in people, 1 from one small study

It selectively switches on the V2 receptor in the collecting ducts of the kidney, which makes the body reabsorb more water and produce more concentrated urine. The changes from natural vasopressin make it last longer and greatly reduce its blood-vessel-narrowing effect. Desmopressin also releases factor VIII and von Willebrand factor from the lining of blood vessels.

Kidneys and urine: Desmopressin switches on one receiver, called V2, in the last stretch of tubing in the kidney where urine gets its final concentration. Those tubes pull water back into the body instead of letting it drain away. Less urine is made, and what is made is more concentrated. That is the drug's main action on the kidney, and it starts within about an hour of a tablet.; Measured directly. One study gave tablets every 8 hours to 36 healthy men who had been given extra water to drink. On the 0.1 mg tablet, urine concentration rose above each man's own starting level by an average of about 515 units. On the 0.4 mg tablet it rose by about 769 units. The unit is mOsm/kg, the standard scale for how concentrated urine is. A separate study covered 10 patients under 18 whose bodies cannot concentrate urine. It reported peak concentrations rather than a rise: about 678 units on a 0.2 mg tablet and about 787 units on a 0.4 mg tablet. That second study was too small to separate any of its doses from the starting point statistically. The effect on night-time urine was then tested against a dummy spray in 1,045 adults aged 50 and over, across two 12-week randomised trials.; Measured in people; Source [05]Source [06]
Blood sodium and body water: Because the water stays in the body instead of leaving as urine, the sodium already in the blood is spread through more fluid. Its concentration falls. Most falls are small and cause nothing at all. A larger fall causes headache, feeling sick, weight gain and confusion. At the extreme it causes fits, coma and death. This is why the US product information carries a warning in a black box. The same labels tell prescribers to check blood sodium within seven days of starting, again at about a month, and periodically after that.; Measured in 1,045 adults aged 50 and over, in two 12-week randomised trials of the nasal spray. A reading of 130 to 134 — just under the normal range — appeared in 12.3% on the higher spray strength against 5.2% on a dummy spray. Readings of 126 to 129 appeared in 2.1% against none, and readings of 125 or under in 1.5% against 0.3%. Measured again in ordinary use, in 3,137 adults over 50 newly prescribed desmopressin. Each was matched one-to-one against someone newly prescribed a different bladder medicine, using insurance records from 2006 to 2017.; Measured in people; Source [01]Source [06]Source [07]
Blood clotting: Desmopressin makes the lining of the blood vessels release its stored supply of two clotting proteins. They are called factor VIII and von Willebrand factor. In mild haemophilia A and type 1 von Willebrand disease that is enough to stop a small bleed, or to cover a minor operation. The store then has to refill, so a dose repeated within a day or two produces a much smaller rise.; The size of the rise depends on the amount given. The US product information for the injection puts the largest rise at 300 to 400 per cent above a person's own starting level. That figure came after an infusion into a vein of 0.4 micrograms per kilogram of body weight. The label does not say who that particular figure was measured in. It does say that at 0.3 micrograms per kilogram, the rise in people with mild haemophilia A and with von Willebrand's disease was not meaningfully different from the rise in healthy people. The rise begins within 30 minutes and peaks between 90 minutes and two hours. The fall-off with repeated dosing was measured separately, in a 2024 Dutch study of people with non-severe haemophilia A having an operation.; Measured in people; Source [01]Source [08]
Face, head and blood pressure: The most common thing a person notices in the first hour or two is a hot, flushed face, sometimes with a headache. The changes made to the molecule strip out most of vasopressin's blood-vessel-narrowing action. It therefore raises blood pressure far less than the natural hormone does. Blood pressure rising was still recorded slightly more often on the nasal spray than on a dummy spray.; Flushing was reported by 54 of 206 adults (26%) who had used desmopressin, and by 7 of the 22 children who had used it. That comes from a Dutch survey of 706 people with non-severe haemophilia A. Blood pressure rising was recorded in 2.6% on the higher-strength nasal spray against 1.1% on a dummy spray, in 1,045 adults over 12 weeks.; Measured in people; Source [06]Source [09]
The numbers on a blood test used in sport: Holding extra water in the body dilutes everything measured in a blood sample. Three figures fall: the packed red cell fraction (haematocrit), the haemoglobin level, and the OFF-hr score, which is worked out from the other two. Those are the figures anti-doping laboratories use to spot blood doping. The World Anti-Doping Agency therefore lists desmopressin under diuretics and masking agents, not under performance drugs, and bans it at all times.; Measured in 8 physically active men who took desmopressin with 1.5 litres of water on one occasion, and the same water alone on another. All three figures fell significantly on the desmopressin occasion. Eight men, one dose, one crossover — nobody has repeated this at scale.; One small study; Source [04]Source [10]

What changed when it was measured

6 findings · 5 measured in people, 1 from one small study

An approved medicine with three uses according to the US product information for DDAVP injection: central diabetes insipidus, haemophilia A with a factor VIII level above 5 per cent, and type 1 von Willebrand disease with factor VIII above 5 per cent. It appears in the Swedish medicines register in several forms, including Minirin melt tablets.

For urine: a tablet starts working at about one hour and is at its strongest between four and seven hours. The 0.1 mg and 0.2 mg strengths last up to about eight hours, and the 0.4 mg strength up to about twelve. For bleeding: the clotting protein begins to rise within 30 minutes of a dose into a vein, and peaks between 90 minutes and two hours. How long the effect lasts depends on how long factor VIII survives in the blood, which the product information puts at about 8 to 12 hours. For the danger: in the five people whose sodium fell to 125 or under in the 12-week nasal-spray trials, it happened anywhere between 6 days and 12 weeks after the first dose. That is why the product information sets sodium checks at seven days and again at about a month, rather than only at the start.

Times people got up in the night to urinate (nasal spray): 1.5 fewer trips a night against 1.2 fewer on a dummy spray. That is a difference of 0.3 trips, with a 95% confidence interval of 0.5 to 0.1 fewer. Halving the number of trips or better happened for 47% on the spray against 27% on the dummy.; 199 adults on the higher spray strength against 204 on a dummy spray, within a 612-patient trial. All were 50 or over, made more than a third of their day's urine at night, and got up at least twice. 12 weeks; Measured in people; Source [06]
Times people got up in the night to urinate (tablet under the tongue): In women, 1.5 fewer trips a night against 1.2 fewer on a dummy tablet. In men, 1.3 fewer against 0.9. Cutting the trips by at least a third happened for 78% of women against 62% on the dummy, and for 67% of men against 50%.; 237 women and 230 men with night-time urination caused by making too much urine at night, two separate randomised trials, 3 months each; Measured in people; Source [11]
Dry nights in children who wet the bed: About 1.8 fewer wet nights a week than on a dummy tablet, with a 95% confidence interval of 1.4 to 2.2 fewer. The reviewers rated that low certainty. Reaching 14 dry nights in a row by the end of treatment was about three times as likely (relative risk 3.18, 95% confidence interval 1.75 to 5.80), rated moderate certainty. Compared with desmopressin, a bedwetting alarm may leave more children dry at follow-up, also rated moderate certainty.; A Cochrane review of 95 trials in 8,473 children aged 5 to 16, of whom 5,434 received desmopressin. The trials were randomised or close to it. The wet-nights figure comes from 16 of them in 1,267 children, and the 14-dry-nights figure from 11 trials in 922 children; Measured in people; Source [12]
Clotting protein (factor VIII) in the blood after one dose: The largest rise the US product information reports is 300 to 400 per cent above a person's own starting level. That was after an infusion into a vein of 0.4 micrograms per kilogram of body weight. The size of the rise goes up with the amount given. There is no dummy comparison for this one: the comparison is each person's own level before and after.; Not stated in the product information for this figure. The same section separately reports that at 0.3 micrograms per kilogram, people with mild haemophilia A and with von Willebrand's disease had a rise no different from that of healthy volunteers; Measured in people; Source [01]
Low blood sodium in ordinary prescribing, outside a trial: 146 episodes per 1,000 person-years against 11 per 1,000 in matched people starting a different bladder medicine. In the first 30 days, 2.50% against 0.13%. Being admitted to hospital with low sodium as the main reason was also far more common on desmopressin.; 3,137 adults over 50 newly prescribed desmopressin, matched one-to-one to 3,137 newly prescribed oxybutynin; average age about 70, median follow-up 51 days; Measured in people; Source [07]
Clotting protein after the dose is repeated: For the middle person, the rise on the second day was 42.9% of the first day's rise, and on the third day 36.4%. The middle half of people fell between 29.2% and 52.5% on the second day, and between 23.7% and 46.9% on the third. Each person was their own comparison, before and after.; 26 people with non-severe haemophilia A, given one dose into a vein each day for up to three days around an operation, alongside factor VIII concentrate. 17 of them contributed the second-day figure — 16 with mild and one with moderate haemophilia A — and 11 contributed the third; One small study; Source [08]

What can go wrong

9 effects, 3 serious

Low blood sodium is the serious risk and carries a boxed warning in the US product information: severe cases can cause seizures, coma, respiratory arrest and death. It must not be used by people with excessive thirst, previous low sodium, SIADH or heart failure, or alongside loop diuretics or steroids, and blood sodium should be checked within seven days, at about a month, and periodically after that. Desmopressin is also banned in sport as a masking agent.

Low blood sodiumSerious: The body keeps water, which thins the sodium in the blood. Small dips cause nothing. Bigger ones cause headache, feeling sick, weight gain, restlessness and confusion. Severe ones cause fits, coma, stopped breathing and death, which is what the warning in the black box says. In the five people whose reading fell to 125 or under, it happened anywhere between 6 days and 12 weeks after the first dose. Four of the five were also taking a steroid.; Measured in two 12-week randomised trials of the nasal spray. A reading of 130 to 134, just under the normal range, in 12.3% on the higher spray strength against 5.2% on a dummy spray. A reading of 126 to 129 in 2.1% against none. A reading of 125 or under in 1.5% — 5 of 341 people — against 0.3%. All five of those worst readings were in people aged 65 or over.; Source [01]Source [06]
Fits brought on by low blood sodiumSerious: Sodium that falls far enough can bring on a fit. The US product information for the desmopressin nose spray says plainly that this is not the form to use for bedwetting. Its stated reason is that reports after marketing showed a higher risk of low sodium, and of fits caused by low sodium, with the spray than with the tablets. The nasal spray later licensed for night-time urination is ruled out for bedwetting for the same reason. Its label names reports of those fits in children given other nose-spray forms.; Not counted as a rate. The evidence is reports that came in after the nose spray was already on sale.; Source [06]Source [13]
Blood clotsSerious: The US product information for the injection lists clots blocking a blood vessel among reported reactions. For one subtype, type IIB von Willebrand disease, the label for the STIMATE nose spray goes further and rules the drug out entirely. In that subtype it can clump platelets together, drop the platelet count and possibly cause a clot.; Not measured as a rate. Listed among the reactions reported after the injection went on sale, without a number attached.; Source [01]Source [14]
Hot, flushed face: A red, hot face soon after a dose. It is listed as a known reaction in the US product information for the injection, and it passes on its own. The survey figures come from people treated for a bleeding disorder; the trials in night-time urination did not report flushing among their common reactions.; 54 of 206 adults (26%) who had used it, and 7 of the 22 children who had used it, in a Dutch survey of 706 people with non-severe haemophilia A.; Source [01]Source [09]
Headache: Usually mild and short. It matters more than the numbers suggest, because headache is also the first sign of sodium falling too far. The two cannot be told apart without a blood test.; 4% on the tablet against 3% on a dummy tablet in the bedwetting trials; 36 of 206 adults (17%) in the Dutch haemophilia survey.; Source [05]Source [09]
Nose discomfort, blocked nose and nosebleeds (nose spray only): Local to the nose and mostly mild. It matters for a second reason. A nose that is inflamed or blocked absorbs more of the drug, so the product information says to stop the spray while a nose problem lasts.; Nose discomfort 5.9% against 4.9% on a dummy spray; blocked nose 2.9% against 1.4%; nosebleeds 2.1% against 1.1%, in 1,045 adults over 12 weeks.; Source [06]
Dry mouth: Common, but almost exactly as common on the dummy tablet, so most of it is not the drug. People in these trials were also cutting down on evening drinks, which dries the mouth on its own.; 12% of women and 14% of men on the tablet under the tongue, against 11% and 13% on a dummy tablet.; Source [11]
Dizziness: Small in absolute terms but clearly above the dummy tablet. It appears in an older group getting up in the night, where a fall is the thing that does the damage.; 2% of women and 3% of men on the tablet under the tongue, against 0% and under 1% on a dummy tablet.; Source [11]
Blood pressure going up: Holding extra fluid loads the circulation. The same product information rules the drug out entirely for people with uncontrolled high blood pressure. It also rules it out for congestive heart failure graded II to IV on the New York Heart Association scale, which covers heart failure that limits physical activity at all.; 2.6% on the higher-strength nasal spray against 1.1% on a dummy spray, in 1,045 adults over 12 weeks.; Source [06]

Who it is known to be dangerous for

The US product information for the nasal spray rules it out for whole groups of people. Anyone whose blood sodium is already low, or has been low before. Anyone who drinks very large amounts of fluid. Anyone taking a loop water tablet such as furosemide, or a steroid swallowed or breathed in. Anyone whose kidneys filter blood at less than about half the normal rate. Anyone with the condition in which the body already makes too much antidiuretic hormone. Anyone in the middle of an illness that upsets fluid and salt balance, such as a stomach bug. Anyone with uncontrolled high blood pressure. And anyone with congestive heart failure graded II to IV on the New York Heart Association scale, which covers heart failure that limits physical activity at all. The nose-spray forms are not the licensed form for bedwetting. The nasal spray licensed for night-time urination was never studied in anyone under 50, so that age group has nothing behind it. That label also states that there are no data on its use in pregnant women.

The amounts the studies used

3 amounts

These are the amounts the studies below gave their participants, and they are here as facts about those studies. They are not a recommendation, not a starting point and not a range to pick from. What a person should take, if anything, is a question for a doctor who knows them.

2024 Dutch study of how much the clotting response falls off when the dose is repeated around an operation, in people with non-severe haemophilia A: 0.3 micrograms per kilogram of body weight into a vein, once a day, alongside factor VIII concentrate; Up to three days in a row, around an operation; Source [08]
The two randomised NOCTIVA nasal-spray trials in adults aged 50 and over who got up at least twice a night to urinate: One spray into one nostril each night. One group was given 1.66 micrograms, a second group 0.83 micrograms, and a third group a dummy spray; 12 weeks; Source [06]
The two randomised NOCDURNA trials of a tablet that dissolves under the tongue, one in women and one in men, for night-time urination: 27.7 micrograms under the tongue in the women's trial; 55.3 micrograms in the men's trial; 3 months; Source [11]

What people report

What follows is what people say online. It is not evidence, it is not graded, and it is not checked by anyone. People who had a bad time and people who are selling something both post more than people for whom nothing happened. It is here because you would go and read it anyway, and knowing who is talking is better than not.

Low sodium is the thing patients talk about, not the drug failing

In the largest survey of people living with central diabetes insipidus, 26% of those on desmopressin — 273 of 994 — said they had been in hospital because of low blood sodium. Patients who routinely skipped or delayed a dose, so that the body could pass water for a while, reported low sodium less often. The comparison group was patients who had never heard of doing that.

Read in International web-based survey of 1,034 patients with central diabetes insipidus, developed by endocrinologists with patient representatives and published in The Lancet Diabetes & Endocrinology in 2022

What the published studies say

The skipping practice is what patients described in a survey. No randomised trial has tested it. The published comparison is only between patients who did it and patients who had not heard of it, which cannot separate the practice from the kind of person who does it. What the product information itself sets out is blood sodium testing at seven days and about a month, not dose skipping.

It works for bleeding, and the flush is the price

Of 187 people with non-severe haemophilia A who answered questions about how well it worked, 171 — 90% — rated it at least moderately effective. In the same survey 42% of adults said they had no side effects at all, while flushing was reported by 26% and headache by 17%. Of the 182 who said which form they preferred, 138 chose the nose spray. The disadvantages people named most were side effects and cost.

Read in Cross-sectional survey of 706 people with non-severe haemophilia A across the Netherlands, published in Research and Practice in Thrombosis and Haemostasis in 2023

Hospitals forget the dose

In the diabetes insipidus survey, 535 people had at some point been told to eat and drink nothing for a medical reason while in hospital. Of those, about one in seven — 71 people — said they were given no desmopressin during that time, and no fluid into a vein either. They reported symptoms of drying out.

Read in International web-based survey of 1,034 patients with central diabetes insipidus, published in The Lancet Diabetes & Endocrinology in 2022

Reports that it stopped working

In the US regulator's own public database of side-effect reports, the drug not working is one of the terms filed most often against desmopressin. Counted through the openFDA interface in August 2026 it came third, behind low blood sodium and headache. Anyone can file a report there, including patients themselves.

Read in FDA Adverse Event Reporting System public dashboard, and the same data through the openFDA query interface

What the published studies say

For bleeding, the published measurement supports the complaint: in a 2024 study, the second day's rise in clotting protein was 42.9% of the first day's in 17 people. But a report in that database is not a finding. The regulator states plainly that a report does not show the drug caused what was reported. The counts also cannot be turned into a rate, because nobody knows how many people took it.

Where to read it yourself

FDA Adverse Event Monitoring System (AEMS) public dashboard, formerly FAERS
Official side-effect reports
The US regulator's searchable file of side-effect reports sent in by doctors, drug companies and members of the public. Counted through its openFDA interface in August 2026, the terms reported most often against desmopressin were low blood sodium (354 reports), headache (267), the drug not working (258) and feeling sick (198).
Reporting is voluntary and uneven. Nobody counts how many people took the drug, so a large number of reports for a widely used medicine means nothing on its own. The regulator says outright that a report is not evidence the drug caused the event. Serious and newsworthy events are reported far more often than dull ones.
Atila et al., international survey of 1,034 people with central diabetes insipidus (The Lancet Diabetes & Endocrinology, 2022)
Published survey of users
The largest published survey of people who take desmopressin for life. It covers side effects, hospital care, quality of life and what patients want the condition called. Among those on desmopressin, 26% had been in hospital with low sodium. Across the whole group, 64% reported a lower quality of life and 80% had met a healthcare professional who confused their condition with diabetes.
It was recruited through patient groups and online, so people already engaged with their condition, and people who had a bad experience, are over-represented. There is no comparison group. It is self-reported throughout: nobody checked the sodium results people described.
Schutte et al., Dutch survey of 706 people with non-severe haemophilia A (Research and Practice in Thrombosis and Haemostasis, 2023)
Published survey of users
A national survey asking people with mild and moderate haemophilia A what desmopressin was actually like to use. It covers how well it worked, which side effects they got, which form they preferred and what they disliked about it.
Everyone answering had already been given the drug by a treatment centre. People who could not tolerate it, or never responded to the test dose, are largely missing. Judgements of how well it worked are the patient's own impression, not a measured clotting result.
The Pituitary Foundation
Patient organisation
A UK charity for people with pituitary conditions, including AVP deficiency. That is the condition previously called central diabetes insipidus, for which desmopressin replaces the missing hormone. It runs an endocrine nurse helpline, local support groups, telephone buddies and a membership network of more than 2,100 people.
A charity with an interest in raising the profile of these conditions, so its material leans towards awareness and reassurance rather than doubt. It carries no evidence grading, and the people posting are a self-selected group who found the charity.
National Bleeding Disorders Foundation
Patient organisation
The US patient organisation for inherited bleeding disorders, formerly the National Hemophilia Foundation. It publishes news and education on von Willebrand disease and haemophilia A.
Its pages carry paid advertising, marked as such, alongside a note that the organisation does not endorse products or manufacturers. That is worth holding in mind on any page about a specific treatment. It is an organisation's voice, not a forum, so individual accounts are ones the organisation chose to publish.
ERIC, The Children's Bowel & Bladder Charity
Patient organisation
The UK charity for children's continence problems. It has a section on bedwetting, a helpline for parents, advice sheets and family webinars. It is the main non-clinical place British parents encounter the tablet form used for bedwetting.
It sells bedwetting alarms and other products through its own shop, which is an interest to hold in mind on any page comparing alarms with medicines. Its advice is written for parents rather than sourced claim by claim.

What nobody has measured

11 unknowns

Whether deliberately leaving out a dose now and then lowers the risk of low sodium — the only evidence is patients comparing themselves in a survey, never a randomised trial.
How much good it does beyond three months for night-time urination. The randomised trials ran 12 weeks and 3 months. The only longer data is an open follow-on study of up to 126 weeks with nobody to compare against.
Whether the roughly one-third-of-a-trip reduction in night-time urination means better sleep. One nasal-spray trial measured the effect on daily life with a questionnaire and found a 4-point difference on a 0-to-100 scale; sleep itself was not measured.
What it does in adults under 50 with night-time urination — the nasal spray licensed for that was never studied below age 50.
What it does in pregnancy: the label for the nasal spray licensed for night-time urination states there are no data in pregnant women.
Whether the fall-off in clotting response with repeated doses differs between the injection, the nose spray and the tablet — the measurement was made only with the injection.
How often clots blocking a blood vessel actually happen: they are listed as a reported reaction with no rate attached.
How often fits caused by low sodium happen with the nose spray: the licence was narrowed on reports that came in after marketing, which cannot be turned into a rate.
How the two treatments for bedwetting compare when children are matched to a treatment by what their own night-time recordings show. A randomised trial in 324 children aged 6 to 14 (NCT03389412) finished in January 2023 and has posted no results to the registry.
Whether the blood-dilution effect used to hide doping behaves the same way in trained athletes: it has been measured in 8 physically active men on one occasion, and not repeated.
What a lifetime of daily use does. The longest follow-up in the US tablet product information is 46 patients treated for 12 to 44 months; nobody has followed people for decades.

Questions people ask

6 questions

Is this an approved medicine or something bought online?: Approved, and it has been for a long time. It was first cleared in the US in 1978, and it is on sale in Sweden and across the EU through national approvals, including Minirin. It comes as a tablet, a tablet that melts in the mouth or under the tongue, a nose spray and an injection. Which one is used depends on what it is being used for.; Source [01]Source [02]
Why does it have a warning in a black box on the label?: Because it can push blood sodium low enough to be dangerous. The wording is that severe low sodium can be life-threatening, and can lead to fits, coma, stopped breathing or death. That is why the label rules the drug out for whole groups of people, and sets blood tests at seven days and about a month after starting.; Source [01]Source [06]
How much difference does it actually make to getting up at night?: Not much, on average. The larger of the two nasal-spray trials ran 12 weeks in 612 adults. The higher spray strength averaged 1.5 fewer trips a night against 1.2 fewer on a dummy spray, a difference of about a third of one trip. What separates the groups more clearly is how many people halved their trips: 47% against 27%. The second trial, in 433 adults, came out close to the same.; Source [06]
Does it cure bedwetting, or only hold it off?: It holds it off. The 2025 Cochrane review of 95 trials in 8,473 children found roughly 1.8 fewer wet nights a week than a dummy tablet while the treatment was being taken. It also found about three times the chance of reaching 14 dry nights in a row. What was measured is the benefit during treatment. Compared with desmopressin, a bedwetting alarm may leave more children dry at follow-up, once treatment has ended.; Source [12]
If it helps a bleed once, will it help again the next day?: Less well. It works by emptying a store of clotting proteins held in the lining of blood vessels, and the store takes time to refill. In a 2024 Dutch study of people having an operation, the second day's rise was 42.9% of the first day's in 17 people, and the third day's was 36.4% in 11. The product information puts the same point as a rule of thumb: doses repeated more often than every 48 hours work less well.; Source [01]Source [08]
Why is it banned in sport if it does not build muscle?: Because it hides other doping. Keeping water in the body dilutes the blood. The diluted sample gives lower readings for the packed red cell fraction, haemoglobin and the OFF-hr score, which are the figures used to detect blood doping. The World Anti-Doping Agency lists it under diuretics and masking agents on the 2026 Prohibited List, banned at all times, in and out of competition.; Source [04]Source [10]

Sources

14 sources

Kidneys & fluid balance · Hormones

16 peptides · strongest evidence first