GLP-1 Weight-Loss Medicines: Who They Are For and Their Risks

GLP-1 weight-loss medicines, such as Wegovy (semaglutide) and Zepbound (tirzepatide), are FDA-approved prescription medicines for adults with obesity, or overweight plus a weight-related health problem. They are used with a reduced-calorie diet and more activity. They carry a boxed warning and real side effects. At Yaso Wellness, Leticia Vargas, MD, reviews whether one is a safe fit for you.

Key facts

  • FDA-approved GLP-1 options for weight: Wegovy injection and Wegovy tablets (semaglutide), Zepbound (tirzepatide), and Foundayo (orforglipron) tablets.
  • Who they are for: adults with a BMI of 30 or higher, or 27 or higher with at least one weight-related condition, along with diet and activity changes.
  • Boxed warning: all carry FDA's highest-level warning about thyroid C-cell tumors seen in rodents.
  • Not for: anyone with a personal or family history of medullary thyroid cancer or MEN 2, or a past serious allergy to the medicine.
  • Birth control and pregnancy: both need planning. See below.

What are GLP-1 medicines for weight loss?

GLP-1 is a hormone your gut makes after you eat. Medicines that act like it slow stomach emptying and help you feel full sooner. Semaglutide acts on the GLP-1 receptor; tirzepatide acts on both GIP and GLP-1 receptors. Orforglipron is a daily GLP-1 pill, and Wegovy also comes as a daily tablet.

Each medicine is one tool in a plan. Obesity is a long-term (chronic) condition, and these medicines are approved for use with healthy eating and activity.

Who qualifies for Wegovy or Zepbound?

FDA labels allow these medicines for adults who have:

  • a BMI of 30 or higher; or
  • a BMI of 27 or higher plus at least one weight-related condition, such as high blood pressure, type 2 diabetes or high cholesterol.

Some labels add other uses. Wegovy is also approved to lower the risk of heart attack, stroke and heart-related death in adults with known heart disease and obesity or overweight. Zepbound is also approved for moderate to severe obstructive sleep apnea in adults with obesity.

Meeting the BMI rule does not mean a medicine is right for you. Dr. Vargas reviews your full health history first.

How much weight do people lose on semaglutide or tirzepatide?

These are study averages. Your results may differ.

  • Wegovy injection (2.4 mg): in a 68-week study of adults without diabetes, people lost an average of 14.9% of body weight, compared with 2.4% on placebo.
  • Wegovy tablets (25 mg): in a 64-week study, people lost an average of 13.6%, compared with 2.4% on placebo.
  • Zepbound (tirzepatide): in a 72-week study, the average loss was 15.0% on 5 mg, 19.5% on 10 mg and 20.9% on 15 mg, compared with 3.1% on placebo.

In all of these studies, people also followed a reduced-calorie diet and increased activity.

What are the side effects of tirzepatide and semaglutide?

Boxed warning. In studies in rodents, these medicines caused thyroid C-cell tumors. It is not known if they cause these tumors, including medullary thyroid cancer, in people. Tell your clinician right away about a lump or swelling in the neck, trouble swallowing, a hoarse voice or shortness of breath.

Common side effects include nausea, diarrhea, vomiting, constipation, stomach pain, tiredness and hair loss. Zepbound can also cause injection-site reactions.

Serious risks listed on the labels include:

  • inflammation of the pancreas (pancreatitis);
  • gallbladder problems, including gallstones;
  • low blood sugar, mainly in people who also take insulin or a sulfonylurea;
  • kidney injury from dehydration after vomiting or diarrhea;
  • severe stomach and bowel side effects;
  • serious allergic reactions;
  • eye problems from diabetes (diabetic retinopathy) in people with type 2 diabetes;
  • a faster heart rate (Wegovy);
  • food or liquid going into the lungs during anesthesia or deep sedation. Tell any surgeon or dentist you take one.

Can I take GLP-1 medicine if I'm on birth control or planning a pregnancy?

This matters for many of our patients.

  • Birth control pills and Zepbound: Zepbound slows stomach emptying, which may make birth control pills work less well. The label advises switching to a non-pill method, or adding a barrier method such as condoms, for 4 weeks after starting and for 4 weeks after each dose increase.
  • Planning a pregnancy: weight loss offers no benefit during pregnancy and may harm a baby. Wegovy should be stopped at least 2 months before a planned pregnancy because it stays in the body a long time. Stop Zepbound when pregnancy is found, and tell your clinician.
  • PCOS: if you have PCOS and meet the label, a GLP-1 medicine may be discussed. See PCOS care.

What happens at a GLP-1 visit at Yaso Wellness?

Your first visit is a medical evaluation, not a quick prescription. Dr. Vargas asks about your weight history, health conditions, family history of thyroid cancer, medicines and pregnancy plans. Lab work may be needed. If a medicine fits, the dose starts low and goes up slowly to ease stomach side effects. Medicine works alongside our 12-week medical weight loss program, not instead of it.

What to ask your clinician

  • Do I meet the FDA label for a GLP-1 medicine?
  • Which medicine fits my health, and why?
  • What side effects should make me call you right away?
  • How does this affect my birth control or pregnancy plans?
  • What happens if I stop the medicine?
  • How will we adjust my other medicines, such as for diabetes or blood pressure?

Frequently asked questions

What is the difference between Wegovy and Zepbound? Wegovy contains semaglutide, which acts on the GLP-1 receptor. Zepbound contains tirzepatide, which acts on both GIP and GLP-1 receptors. Both are weekly shots. Wegovy also comes as a daily tablet. Our guide tirzepatide vs semaglutide compares them.

Can I use a GLP-1 medicine if a family member had thyroid cancer? If a family member had medullary thyroid cancer, or anyone in your family has MEN 2, these medicines should not be used. Other kinds of thyroid cancer are different, so tell your clinician the exact type.

Will I need to take it long term? Often, since obesity is a long-term condition and the labels describe long-term use. Plan with your clinician before you start or stop.

Can I get a GLP-1 prescription by telehealth? Telehealth visits are available if you are physically located in Texas at the time of the visit. A prescription is written only when it meets the same standard as an in-person visit.

Book a visit

Call (210) 903-1030 or Book a visit. In-clinic in San Antonio • Telehealth for people located in Texas

About the clinician

Leticia Vargas, MD, OB/GYN, founder of Yaso Wellness Health Clinic. About Dr. Vargas

Sources

Education only, not medical advice or a diagnosis. In an emergency, call 911.