Semaglutide for beginners

The short version

Semaglutide is a peptide, a short chain of amino acids. It was designed to copy GLP-1, a hormone your gut releases after you eat. A hormone is a chemical messenger that carries a signal from one part of the body to another.

Semaglutide is the active ingredient in FDA-approved prescription medicines. Approved forms include injections and tablets. They are approved for particular uses, including type 2 diabetes and long-term weight management in some adults.

You may also see compounded semaglutide, made to order by a pharmacy. Compounded versions are not FDA-approved, and an FDA-approved version exists. Both need a prescription. They are not the same product, and only the approved one has been reviewed by the FDA.

Is semaglutide a peptide?

Yes. Semaglutide is a chain of thirty-one amino acids. It closely copies the GLP-1 your body makes, with a few links changed on purpose.

Natural GLP-1 is broken down within minutes. Semaglutide's swapped links protect it from the enzyme that does that, and a fatty side chain lets it cling to albumin, a common blood protein. Together they keep it in the body for about a week.

What does it do in the body?

Semaglutide fits into the GLP-1 receptor, the docking point on a cell that the hormone fits into. Researchers describe what follows:

• The pancreas releases more insulin, but mainly when blood sugar is high.
• The pancreas releases less glucagon, a hormone that raises blood sugar.
• The stomach empties more slowly.
• Signals reach parts of the brain involved in hunger and fullness.

That is how the molecule works, not a promise about what it will do for you.

What is the approved medicine for?

The FDA has approved semaglutide medicines for several named uses, each written into the product's official label. In broad terms, they include:

• helping control blood sugar in adults with type 2 diabetes, alongside diet and exercise;
• lowering the risk of serious heart problems, such as heart attack and stroke, in certain adults;
• long-term weight management in certain adults, alongside a reduced-calorie diet and more physical activity;
• lowering certain kidney risks in some adults with type 2 diabetes;
• a liver condition called MASH with scarring of the liver, under a faster form of approval.

Labels change as new uses are approved; the current label is the authority.

What is compounded semaglutide, and where does it stand now?

Compounding is when a pharmacy makes a medicine to order. A compounded medicine is not FDA-approved: the FDA does not check that it works, is safe, or was made well.

For a while, the approved injections were officially in short supply. While a medicine is on the FDA's national shortage list, pharmacies may make copies of it, which is why compounded semaglutide became so common.

On 21 February 2025 the FDA said the shortage was over. The extra room it had allowed during the shortage ended on 22 April 2025 for ordinary compounding pharmacies and on 22 May 2025 for larger outsourcing facilities. As of April 2026, the FDA says semaglutide is not in shortage.

What that means now:

• Since the shortages ended, federal law limits when a pharmacy may compound essentially a copy of an approved drug, and a lower price is not a reason the FDA accepts.
• Compounded versions are not FDA-approved, and FDA-approved versions exist.
• Some sellers use a salt form of semaglutide. The FDA says that is a different ingredient, with no lawful use in compounding that it knows of.

The FDA also says a telehealth company must not call a compounded medicine a generic, call it the same as the approved drug, or say the FDA approved it.

What does a prescription route look like?

1. A clinician licensed in the state where you are sitting reviews your health history, by video or through an online form they can follow up on.
2. The clinician decides whether semaglutide fits you at all. The answer can be no.
3. If it is a yes, the prescription goes to a state-licensed pharmacy, which decides separately whether it can lawfully prepare it. A prescription does not guarantee that a pharmacy will fill it.

The FDA's own advice is short: get a prescription and fill it at a state-licensed pharmacy, which you can look up through its BeSafeRx page. Questions to ask any provider has more.

What does the research show, and what does it not?

Semaglutide has been tested in large clinical trials against a placebo, a dummy treatment. Four well-known ones looked at weight in adults with obesity or overweight (STEP 1), heart outcomes in type 2 diabetes (SUSTAIN-6), heart outcomes in people with heart disease and excess weight but no diabetes (SELECT), and kidney disease in type 2 diabetes (FLOW). Results like these underpin the approvals above.

What the research does not show:

• It tested the approved, factory-made product. Its results do not carry over to a compounded vial, let alone a research-labelled one.
• Stopping matters. In follow-up studies, much of the weight lost tended to come back after people stopped taking it.
• It cannot say how you will respond. Trials describe groups of people, not any one person.

What side effects and cautions are known?

The most common side effects are nausea, vomiting, diarrhoea and constipation, usually mild to moderate and most often while the amount is being raised. The label also carries cautions a clinician checks for:

• A boxed warning about thyroid tumours seen in rodent studies. It has not been shown in people, but the label says semaglutide is not for anyone with a personal or family history of medullary thyroid cancer or a condition called MEN 2.
• Inflammation of the pancreas, called pancreatitis.
• Gallbladder problems, such as gallstones.
• In one trial, eye problems in people who already had diabetic eye disease.
• Pregnancy. The label says to stop at least two months before trying to become pregnant.

Some people have ended up in hospital after measuring compounded versions wrongly. By the end of May 2026 the FDA had 990 problem reports for compounded semaglutide, though a report does not prove the medicine caused the problem.

Asking a licensed clinician about semaglutide

Whether semaglutide could fit you is a question for a licensed clinician. Promise Peptides is a U.S. telehealth platform. Promise prescribes peptides now through licensed U.S. providers. A licensed U.S. provider reviews every request and your health history, then decides whether to prescribe. Not everyone qualifies, and the answer can be no. Prescribed medicines are prepared by licensed U.S. compounding pharmacies. Each pharmacy separately decides whether it can lawfully prepare a prescription; a prescription does not guarantee it will be filled. Compounded medicines are not FDA-approved, and an FDA-approved version of semaglutide exists. How Neo is paid for sets out the rest. U.S. patients only. Availability varies by state and by treatment. Promise is LegitScript-certified. That certification is not FDA approval.

Visit Promise Peptides for semaglutide

Neo may earn money when readers become Promise patients.

Sources

1. Once-Weekly Semaglutide in Adults with Overweight or Obesity (N Engl J Med, 2021)PubMed
2. Semaglutide and Cardiovascular Outcomes in Patients with Type 2 Diabetes (N Engl J Med, 2016)PubMed
3. Semaglutide and Cardiovascular Outcomes in Obesity without Diabetes (N Engl J Med, 2023)PubMed
4. Effects of Semaglutide on Chronic Kidney Disease in Patients with Type 2 Diabetes (N Engl J Med, 2024)PubMed
5. Semaglutide lowers body weight in rodents via distributed neural pathways (JCI Insight, 2020)PubMed
6. Safety of Semaglutide (Front Endocrinol, 2021)PubMed
7. Gastrointestinal tolerability of once-weekly semaglutide in adults with overweight or obesity (Diabetes Obes Metab, 2022)PubMed
8. Drugs@FDA: FDA-Approved DrugsU.S. Food and Drug Administration
9. FDA clarifies policies for compounders as national GLP-1 supply begins to stabilizeU.S. Food and Drug Administration
10. FDA's Concerns with Unapproved GLP-1 Drugs Used for Weight LossU.S. Food and Drug Administration
11. FDA to Telehealth Companies: What to Know When Promoting Compounded DrugsU.S. Food and Drug Administration
12. Compounding and the FDA: Questions and AnswersU.S. Food and Drug Administration
13. 21 U.S.C. 353a, Pharmacy compoundingLegal Information Institute, Cornell Law School
14. BeSafeRx: Locate a State-Licensed Online PharmacyU.S. Food and Drug Administration