How a prescriber decides whether to start you

A first visit for a GLP-1, in person or by video, is mostly questions. Each one maps to a line in the label. Knowing the map makes the visit shorter and your answers better.

Step one: are you in the population

Weight and height for BMI, or a type 2 diabetes diagnosis, and the weight-related conditions the labels name. The label population page covers this in full. Many clinicians will also ask what you have already tried and for how long, because every weight-management label says the drug is used with a reduced-calorie diet and increased physical activity, and because insurers often ask for that history (see insurance basics).

Step two: is there a reason not to

These questions are the contraindications and warnings, sections 4 and 5 of each label, turned into plain English.

• Thyroid. Have you, or has anyone in your family, had medullary thyroid carcinoma? Has anyone been diagnosed with Multiple Endocrine Neoplasia syndrome type 2? Either is a contraindication in all four labels. The boxed warning behind it comes from rodent studies; the labels say it is unknown whether the drugs cause these tumors in humans.
• Pancreas. Have you had pancreatitis? The labels report acute pancreatitis in trials and say the drugs have not been studied in people with a history of it (section 5.x, acute pancreatitis).
• Gallbladder. Gallstones or gallbladder surgery? Acute gallbladder disease is a warning in each label, more so with rapid weight loss.
• Stomach and bowel. Gastroparesis or severe gastrointestinal disease? The labels note the drugs delay gastric emptying and were not studied in severe GI disease; the Ozempic label says it is not recommended in that group.
• Kidneys. Any kidney disease? The warning is acute kidney injury, mostly in people who became dehydrated from vomiting or diarrhea (see hydration).
• Eyes, if you have diabetes. Diabetic retinopathy? The semaglutide labels carry a warning about retinopathy complications in people with type 2 diabetes, based on SUSTAIN 6.
• Mood. History of depression or suicidal thoughts? Earlier versions of the Wegovy and Zepbound labels told prescribers to monitor for depression and suicidal thoughts. FDA removed that warning in the February 2026 revisions after reviewing the evidence, but a good prescriber still asks, and you should still answer.
• Allergy. Any serious allergic reaction to a GLP-1 before? Prior serious hypersensitivity is a contraindication.
• Pregnancy. Pregnant, breastfeeding, or planning? The Wegovy label says to stop the drug at least 2 months before a planned pregnancy because of its long wash-out (section 8.1). Tirzepatide has a specific instruction for people using oral contraceptive pills: switch to a non-oral method or add a barrier method for 4 weeks after starting and for 4 weeks after each dose increase, because absorption of the pill may fall (Zepbound section 7.1).
• Other medicines. Insulin or a sulfonylurea (low blood sugar risk, section 5.4). Any oral medicine with a narrow margin, because slower stomach emptying can change absorption (section 7).
• Upcoming procedures. Any surgery or sedation planned? The labels now warn about pulmonary aspiration during general anesthesia or deep sedation and tell you to inform the team doing the procedure (Wegovy section 5.x, Zepbound section 5.x).
• Heart rate and blood pressure. A baseline pulse and blood pressure, because the labels report a mean resting heart rate increase.

None of these is a trick question. Answer them as fully as you can, including family history you are unsure about.

Step three: labs

No label requires a specific blood panel before the first dose. Clinicians order labs for two reasons: to make sure a warning does not already apply, and to have a baseline to compare against later. The commonly ordered set is a glucose measure (A1c or fasting glucose), a lipid panel, a metabolic panel covering kidney and liver function, and sometimes thyroid function or a pregnancy test. Which ones, and which numbers matter, is the subject of the network's lab site, GLP-1 Lab Guide, which also has a pre-visit lab checklist you can take with you. Telehealth programs vary a great deal on whether they require labs at all; that is a fair thing to ask them and a fair thing to compare.

Step four: which product, and which dose

If you are in the population and nothing in step two stops you, the prescriber chooses between molecules and between brand and compounded product, then writes a starting dose. Every label starts at the same initiation dose regardless of weight: 0.25 mg for semaglutide, 2.5 mg for tirzepatide, each for four weeks (section 2.1). There is no weight-based starting dose. A compounded product has no label, and the pharmacy's concentration and instructions govern how much you draw up; compounded products are not FDA approved and are not interchangeable with brand products.

What they watch after you start

The label tells the prescriber to follow tolerability at each step before increasing (section 2.1), which is why a check-in around week four or five is standard: that is when blood levels reach steady state (section 12.3). Expect to be asked about nausea, vomiting, bowel habit, fluid intake, mood, and any of the warning symptoms on the when to call page. Weight is recorded, but a good clinician will not judge the first month by it.

Bring this list

Write down before the visit: your height and most recent weight; every diagnosis you have been given; every medicine and supplement you take; your family history of thyroid and endocrine cancers as far as you know it; past pancreatitis or gallbladder problems; any surgery in the next few months; and the questions on the talking to your prescriber page.