Will it make me lose weight?

Barely, in the one adult trial that tested it properly. 172 adults with obesity and high insulin output were randomised to dummy injections or one of three monthly doses for six months. The 40 mg and 60 mg groups ended about 1.9 to 2.0% of body weight below the dummy group. From an average starting weight of about 110 kg, that is roughly two kilograms. The 20 mg group showed no reliable difference. Loose stools hit 28% to 36% of the drug groups and gallstones 10% to 18%. That trial was run by Novartis, which makes the drug. A second trial gave 60 children aged 6 to 17 who became obese after brain injury six months of monthly injections. Their BMI changed by 0.1 against 0.0 on salt water, and Novartis's own label states that effectiveness was not demonstrated. A third of those children developed new gallstones.

It gets talked about in gyms for shrinking the belly that comes with growth hormone use. Is there anything behind that?

Nothing published. A search of the medical literature for this review turned up no human study of octreotide for abdominal size, body shape or body composition in people using growth hormone. The only human weight data are the 172-adult obesity trial and the two trials in children with obesity after brain injury, none of which measured that. What is documented is the cost: gallstones or sludge in about half of long-term users, and a third of the children in the six-month paediatric trial developing new stones.

Is there a capsule version instead of an injection?

A capsule form exists and works, but it has become harder to get. In a trial of 56 adults with acromegaly already controlled on injections, 58.2% kept normal IGF-1 on the capsules against 19.4% on dummy capsules over 36 weeks. The European Medicines Agency authorised the capsule, Mycapssa, on 2 December 2022; the authorisation was withdrawn on 26 February 2025 at the manufacturer's own request for commercial reasons, not because of a safety problem, with a commitment to keep supplying patients already on it.

Does it shrink the pituitary tumour, or just control the hormone?

The hormone control is well measured; the tumour shrinkage is not. Two studies in 143 adults with acromegaly who had not been treated before reported median tumour shrinkage of 20.6% at 24 weeks in one and 24.5% at 24 weeks rising to 36.2% at 48 weeks in the other. Everyone in both studies got the drug and everyone knew it, so there is no untreated group to say what those tumours would have done anyway. The label for the older short-acting injection is blunter still: it states that reduction in tumour size or growth rate was not shown in the trials done with that form.

Does the body get used to it and stop responding?

Antibodies against octreotide appear in up to 25% of people who take it. The label states these do not change how well it works, though in two acromegaly patients the effect of each injection lasted about twice as long. Losing control is a real problem for a different reason. In the six-month carcinoid trial, 35% to 40% of people on the monthly depot needed extra short-acting injections in any given month to control a flare. Over the whole six months, 50% to 70% needed them at some point. This happened even though the drug had reached a steady level in the blood.

Why does it cause gallstones so often?

Because it removes the signal that makes the gallbladder squeeze. When food arrives in the gut, the gut releases a hormone called cholecystokinin that tells the gallbladder to push bile out. Octreotide blocks that release. In nine adults with acromegaly, gallbladder emptying dropped by 57% within 24 hours of the first dose; six months in, four of the nine still had badly impaired emptying, and three of those four had developed stones or sludge. Bile that never moves thickens, and thick bile makes stones.

Therapeutic

Octreotide

Also known as Sandostatin · Sandostatin LAR · Mycapssa

Approved medicine

21 of 51 peptides sit at this level

Category: Therapeutic
Doping status: Not banned in sport
Sources: 17

Octreotide is a laboratory-made copy of somatostatin, the body's own "stop" hormone, rebuilt so it survives in the blood for hours instead of minutes. It has been an approved prescription medicine since 1988. It is given for acromegaly, a disease where a pituitary tumour makes too much growth hormone, and for rare hormone-producing tumours in the gut that cause flushing and watery diarrhoea. For those uses the evidence is large, includes trials against dummy injections, and is written into the approved labelling with the numbers attached. For almost anything else it gets talked about, including body weight, the picture is either untested or was tested and the effect was small or absent.

OctreotideWhat 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 ring-shaped eight-amino-acid peptide that mimics the body's own somatostatin but lasts longer. According to the US label's chemical name it contains two mirror-image amino acids and a modified tail, and is closed into a ring by a sulphur bridge between positions 2 and 7. It therefore cannot be written correctly in the standard one-letter code.

How it is sold, and whether it is legal

Sold as: Injection under the skin or into a vein; a long-acting depot into muscle; an oral capsule exists in some countries.
Legal status in the EU: An approved prescription medicine in Sweden and the EU through national approvals. ATC code H01CB02 in the WHO index. Sandostatin, Sandostatin LAR and generic octreotide products all appear in the Swedish medicines register.

What it does in your body

6 parts of the body · all measured in people

It switches on somatostatin receptors, mainly two of the five subtypes. This blocks the release of growth hormone, glucagon, insulin and two other signalling substances, which is the basis both for its effect in acromegaly and for the symptom relief it gives in hormone-producing tumours.

Growth hormone, from the pituitary gland: Octreotide switches off the pituitary gland's release of growth hormone. In ten healthy men given a single injection under the skin of 50 or 100 micrograms, the normal bursts of growth hormone stopped completely for five hours, while nothing changed after a dummy injection. Given repeatedly in acromegaly, it holds growth hormone down month after month, and IGF-1 — the growth signal the liver makes in response to growth hormone, and the thing doctors actually measure — falls with it.; Single doses measured in 10 healthy men against dummy injections; the long-running effect measured in 261 adults with acromegaly across three trials, 209 of them treated for 48 weeks and 96 for more than 108 weeks.; Measured in people; Source [07]Source [08]
Stomach and gut: This is where most people notice it, and it starts early. Loose stools, cramping pain and wind appear mostly in the first month and then settle. It also switches off the enzymes the pancreas sends into the gut to digest fat, so some fat passes through undigested — stools can turn pale, greasy and hard to flush.; Gut complaints counted in 261 adults with acromegaly on the monthly depot and 114 on the three-times-daily injection, treated for roughly one to four years: loose stools in 36.4% and 57.9%, abdominal pain in 29.1% and 43.9%. Fat in the stool measured directly in 8 adults with acromegaly over four months, rising from 7 to 12 grams a day and returning to normal after stopping.; Measured in people; Source [08]Source [09]
Gallbladder and bile: The gallbladder is a small bag that squeezes bile into the gut when a meal arrives. Octreotide blocks the meal signal that makes it squeeze, so bile sits still. Within a day of the first dose the gallbladder empties far less; over months the standing bile thickens into sludge and then into stones. Most people never feel this happening, which is why the label tells doctors to scan for it.; Gallbladder emptying measured by scan in 9 adults with acromegaly, 24 hours after the first dose and again at six months. Stone and sludge rates were counted across the trials behind the label. Of people new to the drug on the short-acting injection, 63% developed some abnormality of the bile system: 27% stones, 24% sludge without stones, 12% a widened bile duct. Of acromegaly patients on the monthly depot, most treated for 12 months or longer, 52% developed new abnormalities, with new stones in 22%.; Measured in people; Source [08]Source [10]
Blood sugar: Octreotide blocks the release of insulin, which lowers blood sugar, and of glucagon, which raises it. Because it blocks both, blood sugar can move in either direction and which way it goes is not predictable from the dose. In practice the more common direction is upwards.; Measured in the acromegaly trials behind the label: blood sugar too high in about 15% and too low in about 2%. In carcinoid tumour patients on the monthly depot, too high in 27% and too low in 4%. In the 172-adult obesity trial, six months on the drug left blood sugar higher across the three hours after a sugar drink than dummy injections did (P = 0.0028). It also raised the three-month blood-sugar average by 0.17 to 0.23 percentage points.; Measured in people; Source [08]Source [11]
Heart rate: The resting heart slows. In some people it slows past the point doctors call abnormal, and the electrical signal that travels through the heart can be delayed or become irregular. The label is explicit that it cannot separate the drug from the underlying illness here, because many of the people studied already had heart disease.; Measured on heart tracings in the trials behind the label: a resting rate below 50 beats a minute in 25% of acromegaly patients on the short-acting injection, with conduction delays in 10% and irregular rhythms in 9%. In carcinoid patients on the monthly depot, a slow rate in 19%, conduction delays in 9% and irregular rhythms in 3%.; Measured in people; Source [08]
The thyroid: Octreotide also switches off TSH, the pituitary signal that tells the thyroid gland to work. In some people the thyroid then makes too little hormone, which shows up on a blood test before it shows up as tiredness or cold intolerance. A minority end up needing thyroid hormone as a tablet.; Measured in acromegaly patients on the short-acting injection: 12% developed an underactive thyroid on blood testing, 8% developed a swollen thyroid gland, and 4% had to start thyroid hormone replacement. On the monthly depot it was reported as a side effect in 2%, with a swollen gland in 2%.; Measured in people; Source [08]

What changed when it was measured

10 findings · 9 measured in people, 1 where studies in people disagree

Sandostatin (NDA 19667) was approved by the FDA on 21 October 1988. The acromegaly approval applies to patients who have not responded well enough to, or cannot have, surgery, pituitary radiation and bromocriptine; the other approved uses are spreading carcinoid tumours and VIPoma with watery diarrhoea. For the newer oral form, CHIASMA OPTIMAL (56 patients already responding to injections) showed 58.2 per cent had normalised IGF-1 at week 36, and CH-ACM-01 (155 patients) showed 65 per cent kept normal growth hormone and IGF-1 levels after switching from injection to capsule.

Fast at the start, slow at the end. In ten healthy men, a single injection under the skin stopped growth hormone bursts for five hours; the label puts the useful effect of one short-acting injection at up to 12 hours, which is why that form has to be given three times a day. The gallbladder reacts just as quickly — in nine adults with acromegaly it was squeezing 57% less within 24 hours of the first dose. The monthly depot works on a different clock. After one injection into muscle, blood levels dip for three to five days, then climb to a plateau about two to three weeks in. The drug only reaches a steady level after the third monthly injection. Gut symptoms cluster in the first month and new cases are uncommon after that. Gallstones and sludge build up over months to years: 52% of people on the short-acting injection for 12 months or longer had stones or sludge. The label says that rate tracks how long someone has been on the drug rather than the dose.

How long tumours in the gut took to grow: Median time before the tumour grew was 14.3 months on octreotide against 6.0 months on dummy injections. At six months, 66.7% of the octreotide group still had a tumour that had not grown, against 37.2% of the dummy group.; 85 adults with a spreading, well-differentiated neuroendocrine tumour of the middle gut who had never been treated, followed until the tumour grew or the person died; Measured in people; Source [12]
How long people lived, in that same tumour trial: Seven deaths in the octreotide group and nine in the dummy group. The comparison came out at a hazard ratio of 0.81 with a range from 0.30 to 2.18 — a range wide enough to include a real benefit, no difference, and harm, so the trial did not answer the question.; The same 85 adults, at the point of the reported analysis; Measured in people; Source [12]
Keeping acromegaly under control with a monthly injection under the skin: IGF-1 stayed at or below the normal upper limit in 72.2% of people given octreotide against 37.5% given dummy injections (P = 0.0018). Combined growth hormone and IGF-1 control was 70.0% against 37.5% (P = 0.0035).; 72 adults with acromegaly already stable on standard monthly injections, randomised two to one, 24 weeks; Measured in people; Source [13]Source [14]
Keeping acromegaly under control with a capsule instead of an injection: IGF-1 stayed normal in 58.2% of people on the capsules against 19.4% on dummy capsules (P = 0.008). Growth hormone stayed below 2.5 ng/mL in 77.7% against 30.4% (P = 0.0007). The dummy group lost control after a median of 16 weeks; the capsule group had not reached that point when the trial ended.; 56 adults with acromegaly whose disease was already controlled by injected somatostatin drugs, randomised one to one, 36 weeks; Measured in people; Source [15]
Growth hormone and IGF-1 when switching from daily injections to a monthly depot: In 88 people followed through 27 to 28 monthly injections, IGF-1 was normal in 51% on the depot against 41% on the daily injections they had been taking. In a second group of 122 people followed through 12 monthly injections, IGF-1 was normal in 67% on both. Both arms were octreotide — nobody in these trials was given a dummy.; 210 adults with acromegaly who completed every injection across three trials, all of whom had already been on the short-acting injection before enrolling and most of whom had responded to it; Measured in people; Source [08]
Daily stools and flushing episodes in carcinoid syndrome: Average daily stools fell from between 4.0 and 4.9 at the start to between 2.1 and 2.8 at the last visit, and daily flushing episodes fell from between 3.0 and 6.1 to between 0.6 and 1.0. The 26 people kept on the older three-times-daily injection went from 3.7 to 2.6 stools and 3.0 to 0.5 flushes. There was no dummy group — everyone in this trial received octreotide in one form or another, and all of them had already been shown to respond to it.; 93 adults with carcinoid syndrome already responding to octreotide, 6 months; Measured in people; Source [08]
Needing extra rescue injections despite being on the monthly depot: In any given month after the drug reached a steady level in the blood, about 35% to 40% of people on the monthly depot needed extra short-acting injections. These were usually for a few days, to control a flare of symptoms. Over the whole six months about 50% to 70% needed them at some point. The rate in the group randomised to stay on the short-acting injection was similar.; The same 93 adults with carcinoid syndrome, 6 months; Measured in people; Source [08]
Size of the pituitary tumour in acromegaly: Median shrinkage of 20.6% at 24 weeks in one study of 49 people, and 24.5% at 24 weeks rising to 36.2% at 48 weeks in a second study of 94 people. Neither study had a comparison group — everyone was given the drug and the scans were read without a control to measure against.; 143 adults with acromegaly who had not been treated before, two open-label studies, 48 weeks; Measured in people; Source [08]
Body weight in adults with obesity who make too much insulin: The gap against dummy injections was 1.98% of body weight in the 40 mg group and 1.87% in the 60 mg group. Everyone started at about 110 kg on average, so that gap is roughly two kilograms in six months. The 20 mg group ended 1.03% below the dummy group, which was not a reliable difference (P = 0.0721), and the authors state that 40 mg was the lowest dose that separated from dummy at all. Loose stools occurred in 28% to 36% of the drug groups against 18% on dummy, and gallstones in 10% to 18% against 7%.; 172 adults with obesity and high insulin output, randomised to dummy injections or one of three monthly doses, 6 months; the trial was run and part-authored by Novartis, the manufacturer; Measured in people; Source [11]
Body weight in children who became obese after brain injury or brain tumour treatment: The two trials point different ways. In the smaller one, weight rose 1.6 kg on octreotide against 9.1 kg on dummy injections over six months (P < 0.001) and BMI fell 0.2 against a rise of 2.2 (P < 0.001). In the larger one, run by the manufacturer, BMI rose 0.1 on octreotide against 0.0 on salt water, and the label states plainly that effectiveness was not demonstrated. New gallstones appeared in 33% of the children in that larger trial.; 18 children in the smaller trial, 6 months; 60 children aged 6 to 17 in the larger trial, 6 months; Studies in people disagree; Source [08]Source [16]

What can go wrong

12 effects, 3 serious

Effects on the gallbladder and bile ducts are the most characteristic side effect — in the study material behind the US label, 63 per cent had abnormalities, of which 27 per cent were gallstones and 24 per cent sludge without stones. Other common effects are a slow heart rate, diarrhoea, loose stools, nausea, abdominal pain, high blood sugar and an underactive thyroid. Because it blocks the release of both insulin and glucagon, blood sugar can swing in either direction.

Gallstones, sludge and the problems they causeSerious: The gallbladder stops emptying, bile thickens, and stones form silently over months. Most people never notice. A few developed inflamed gallbladders, infected bile ducts, blocked bile flow, inflamed liver or inflamed pancreas during treatment or after stopping; one person died of an infected bile duct in the trials behind the label. The label instructs doctors to scan periodically and to stop the drug if a complication is suspected.; 63% of people new to the drug in the short-acting injection trials developed some abnormality of the bile system; 52% of acromegaly patients on the monthly depot did, with new stones in 22%. About 1% needed their gallbladder removed.; Source [08]
A heart that beats too slowly or out of rhythmSerious: Usually silent and picked up on a heart tracing. The label notes that most of the people studied already had heart disease, so it does not claim the drug caused these. One person with severe heart failure got worse when the drug was started, improved when it was stopped, and got worse again when it was restarted. Heart attack, cardiac arrest and atrial fibrillation have been reported since the drug went on sale, without a known rate.; A resting rate below 50 beats a minute in 25% of acromegaly patients on the short-acting injection; conduction delays in 10% and irregular rhythms in 9%. In carcinoid patients on the monthly depot, 19%, 9% and 3%.; Source [08]
A gut reaction severe enough to look like a blockageSerious: A swelling belly, severe pain high in the abdomen, and a stomach wall that goes tense to the touch — the picture of a blocked bowel. Actual bowel obstruction, stomach ulcers and failure of the pancreas to make digestive enzymes have all been reported since the drug went on sale. So has anaphylaxis, the whole-body allergic reaction that can drop blood pressure.; Described as rare; no rate given in the label.; Source [08]
Loose stools and diarrhoea: The most common complaint by a wide margin. It appears mostly in the first month and new cases are uncommon after that; most cases were mild to moderate. It is worse at higher doses. Only 2.6% of people on the short-acting injection in the US trials stopped treatment because of gut symptoms, and nobody on the monthly depot did.; 36.4% of 261 acromegaly patients on the monthly depot and 57.9% of 114 on the three-times-daily injection. In a trial that compared the monthly depot against pituitary surgery, 47.4% of 76 people on the drug against 3.1% of 64 after surgery.; Source [08]
Belly pain and cramping: Comes on in the same first month as the loose stools and usually settles with them. In carcinoid patients it was reported alongside nausea and wind in 27% to 38%.; 29.1% of 261 acromegaly patients on the monthly depot and 43.9% of 114 on the three-times-daily injection. 25.0% against 3.1% in the trial against surgery.; Source [08]
Blood sugar going too high: The drug blocks the release of both insulin and the hormone that opposes it, and in most people the balance tips upwards. Diabetes has been reported as a new diagnosis since the drug went on sale. The label tells doctors to check blood sugar when treatment starts and whenever the dose changes.; About 15% of acromegaly patients and 27% of carcinoid patients on the depot.; Source [08]
Blood sugar going too low: Less common than the opposite problem, but it matters more for anyone already taking insulin or diabetes tablets, because those lower blood sugar too. The label records that doses of 2.5 mg given under the skin — many times what any trial used — have caused low blood sugar along with flushing, dizziness and nausea.; About 2% of acromegaly patients and 4% of carcinoid patients on the depot.; Source [08]
Wind and constipation: The monthly depot causes more of both than the daily injection does, and less nausea. In carcinoid patients, constipation or vomiting was reported in 15% to 21%.; Wind in 25.7% and constipation in 18.8% of 261 acromegaly patients on the monthly depot; 13.2% and 8.8% on the three-times-daily injection.; Source [08]
An underactive thyroid: The drug turns down the pituitary signal that drives the thyroid. It shows up on a blood test before it shows up as tiredness or feeling cold, which is why the label asks for thyroid tests at the start and periodically after.; On the short-acting injection: 12% on blood testing, 8% with a swollen gland, 4% needing thyroid hormone as a tablet. On the monthly depot: reported as a side effect in 2%.; Source [08]
Pain where the injection goes in: The label calls it generally mild to moderate and short-lived, usually about an hour, and it gets more common at higher doses. Patient surveys report something quite different — see the section on what people report.; In acromegaly patients on the monthly depot, 2% at the 10 mg dose, 9% at 20 mg and 11% at 30 mg. In carcinoid patients who kept a diary, about 20% to 25% at 10 mg and about 30% to 50% at 20 mg and 30 mg.; Source [08]
Greasy, pale, hard-to-flush stools: Caused by undigested fat: the drug switches off the pancreas enzymes and the bile that break fat down. In 8 adults with acromegaly, fat in the stool rose from 7 to 12 grams a day at the higher dose and went back to normal after stopping. The label asks doctors to check for pancreas enzyme failure if this appears or worsens.; Indigestion, greasy stools, discoloured stools and a constant urge to open the bowels were each reported in 4% to 6% of patients.; Source [08]Source [09]
Low vitamin B12: Vitamin B12 levels and the test of how well B12 is absorbed have both come back abnormal in some people on the drug. No trial has put a number on how often.; Not measured as a rate. The label reports it only as something seen in some patients and asks for monitoring.; Source [08]

Who it is known to be dangerous for

The two labels differ on outright bars. The label for the short-acting Sandostatin injection lists one: sensitivity to the drug or to anything else in it. The label for the monthly depot lists none at all. Beyond that there are named groups where harm is documented rather than theoretical. Transplant patients on ciclosporin: octreotide lowers ciclosporin levels in the blood and rejection of the transplanted organ has been reported. Anyone taking insulin or diabetes tablets: octreotide blocks insulin release and blood sugar can move sharply in either direction. Anyone on a beta blocker or another drug that slows the heart, because the effects add up. Anyone about to be given lutetium-177 dotatate, a radioactive cancer treatment that has to reach the same docking points on the tumour. The label says octreotide has to be stopped at least four weeks before each dose of it, or it gets in the way. Children under two: serious events including low oxygen, a severe bowel condition in newborns and deaths have been reported since the drug went on sale. Those children were mostly very ill already, so the link to the drug is not established. In pregnancy, the label states the data are too limited to say anything either way.

The amounts the studies used

8 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.

The three trials behind the monthly depot's approval in acromegaly, in people already responding to the short-acting injection: 20 mg or 30 mg injected into the buttock muscle once every 4 weeks; Up to 27 to 28 injections, about two years; Source [08]
The short-acting injection those same acromegaly patients were on before switching to the depot: 100 micrograms or 200 micrograms injected under the skin, three times a day; Weeks to as long as 10 years before the trials began; Source [08]
PROMID, tumour growth in neuroendocrine tumours of the middle gut, 85 adults: 30 mg injected into muscle once a month; Until the tumour grew or the person died; Source [12]
The phase 3 carcinoid syndrome trial, in which 67 of the 93 adults were randomised to one of three fixed monthly amounts and the other 26 stayed on the older injection: 10 mg, 20 mg or 30 mg injected into muscle every 28 days; 6 months, with a 12-month extension in 78 of them; Source [08]
CHIASMA OPTIMAL, the oral capsule trial in 56 adults with acromegaly: 40 mg a day taken by mouth; some participants were moved to 60 mg or 80 mg a day during the trial; 36 weeks; Source [15]
ACROINNOVA 1, the newer under-the-skin depot, given to 48 of the 72 adults with acromegaly in the trial: 20 mg injected under the skin once a month; 24 weeks of blinded treatment; Source [13]
The Novartis weight trial in 172 adults with obesity and high insulin output, randomised to one of three fixed monthly amounts or dummy injections: 20 mg, 40 mg or 60 mg injected into muscle once a month; 6 months; Source [11]
The 60-child trial in obesity after brain injury, aged 6 to 17, which did not show an effect: 40 mg injected into muscle every 4 weeks; 6 months; Source [08]

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.

The injection hurts for days, not for an hour

In a survey of 195 people with acromegaly on monthly injections, 70% reported pain at the injection site. 36% said the pain lasted for days and 15% said it lasted a week. People on octreotide reported longer-lasting pain than people on the competing drug lanreotide.

Read in Patient-reported outcomes survey of 195 adults with acromegaly recruited from nine specialist pituitary centres in Germany, the UK and the Netherlands, published 2016