Boxed warning
The reference versions of these medicines carry the FDA's strongest form of warning. In animal testing they caused thyroid tumors. It is not known whether they do the same in people, but anyone with a personal or family history of a particular thyroid cancer should not take them.
Who should not take these medicines
- A personal or family history of medullary thyroid cancer
- A rare inherited condition called Multiple Endocrine Neoplasia type 2
- A previous serious allergic reaction to semaglutide or tirzepatide
- Pregnancy, trying to conceive, or breastfeeding
Common side effects
- Nausea
- The most common one, usually strongest in the days after a dose increase.
- Vomiting and diarrhea
- Normally early and temporary. Tell your doctor if it carries on.
- Constipation
- Fluids, fiber and movement help. Your doctor can advise.
- Stomach pain, reflux, burping
- Smaller, slower, lower-fat meals usually settle this.
- Tiredness and headache
- Often a sign you are not eating or drinking enough.
Serious risks
Seek medical attention if any of these occur.
- Inflammation of the pancreas
- Severe stomach pain that will not go away, with or without vomiting. Stop taking it and get medical help.
- Gallbladder problems
- Losing weight quickly raises the risk of gallstones. Pain under your right ribs, fever or yellowing skin needs urgent attention.
- Low blood sugar
- The risk rises sharply if you also take insulin or certain diabetes tablets. Those doses need reviewing before you start.
- Kidney problems
- Usually caused by dehydration from vomiting or diarrhea. Keep your fluids up.
- Eye changes if you have diabetes
- If you already have diabetic eye disease, improving your blood sugar quickly can make it worse for a time. Tell your doctor.
- Slowed stomach emptying
- This can become a problem in its own right, and it matters before surgery. Tell any surgeon or anaesthetist that you are taking this medicine.
Interactions
Because these medicines slow how quickly your stomach empties, they can change how fast other tablets are absorbed. Give your doctor your full medication list, including insulin, diabetes tablets, thyroid medication and the contraceptive pill.
Peptides
These peptides are not FDA-approved for the uses described. Compounded medications are not reviewed by the FDA for safety, effectiveness or quality, and availability varies by state and by pharmacy. Every description below covers what a peptide is studied for. None of it is a claim of proven benefit.
Each peptide page carries its own risk information and the conditions under which it should not be used. Start from the peptide catalogue.
By product
Semaglutide Injection
Weekly, injectable GLP-1 treatment for weight loss. Full prescribing and risk information is on the Semaglutide Injection page.
Semaglutide Tablets
Daily, needle-free GLP-1 treatment for weight loss. Full prescribing and risk information is on the Semaglutide Tablets page.
Tirzepatide Injection
Weekly, injectable dual-action treatment for weight loss. Full prescribing and risk information is on the Tirzepatide Injection page.
Tirzepatide Tablets
Daily, needle-free dual-action treatment for weight loss. Full prescribing and risk information is on the Tirzepatide Tablets page.
Reporting a side effect
Tell your care team through your account, or contact support. You may also report side effects directly to the FDA at 1-800-FDA-1088 or via fda.gov/medwatch.