Weight Loss Medications: Introduction

Weight loss medication has changed a great deal in the past few years. The newer injections work far better than anything we had before, and they come with real requirements and real risks.

This page walks through the main options, who qualifies, what to expect, and what you need to know about safety before you start.

Explore each medication

The main weight-loss medication options

Several medications are FDA-approved for long-term weight management. They differ in how they work, how you take them, and how much weight they typically take off.

Semaglutide (Wegovy)

Semaglutide is a once-weekly injection.¹ It copies a natural gut hormone called glucagon like peptide-1, or GLP-1.

That hormone does three useful things. It tells your brain you are full. It slows how fast your stomach empties. And it helps steady your blood sugar. Together those effects make it much easier to eat less without white-knuckling it.

Tirzepatide (Zepbound, Mounjaro)

Tirzepatide is also a once-weekly injection, sold as Zepbound for weight management and Mounjaro for diabetes.²

It works on two pathways rather than one. Tirzepatide is a GIP and GLP-1 receptor agonist, meaning it activates both hormone systems at once. In trials, that dual action produced more weight loss than GLP-1 alone. See our comparison of Wegovy vs. surgery outcomes for how these drugs stack up against sleeve gastrectomy and gastric bypass over the long term.

Zepbound also carries an FDA indication no other weight-loss drug has: treating moderate to severe obstructive sleep apnea in adults with obesity. If you have both obesity and sleep apnea, that matters.

Older and alternative medications

Phentermine, Contrave, orlistat, and diethylpropion are still in use. They cost far less than the injections. They also produce less weight loss on average. For some patients, particularly those paying out of pocket, they are the right place to start.

Who is a candidate for weight-loss medication?

These drugs are approved for adults with a body mass index (BMI) of 30 or higher. A BMI of 27 or higher also qualifies if you have a weight-related condition such as type 2 diabetes, high blood pressure, or sleep apnea. Weight loss meds are often used off-label for patients with a BMI below 27. BMI is only the starting point. Each drug carries its own cautions, and some depend on your personal and family medical history. We go through that history with you before prescribing anything. See our bariatric surgery requirements for a fuller breakdown of BMI thresholds and comorbidities.

What to expect on weight-loss medication

You start at a low dose and step up gradually over several weeks. That slow ramp is deliberate, and it keeps side effects manageable.

Most side effects are digestive. Nausea, diarrhea, constipation, and vomiting are the common ones, and they are usually mild to moderate. They tend to ease as your body adjusts.

One expectation worth setting early: these drugs treat obesity as the ongoing condition it is. Research consistently shows that much of the lost weight comes back when treatment stops. Think of this as long-term care, not a course of antibiotics. If you have already had an operation, our guide to managing weight regain after bariatric surgery explains how these medications are used after a sleeve or bypass.

Safety: what to know before you start

These are effective medications with a well-documented safety profile. They also carry warnings you should understand before your first injection, not after.

The thyroid tumor warning

Semaglutide and tirzepatide both carry a boxed warning, which is the FDA's strongest.

In studies, these drugs caused thyroid C-cell tumors in rats. Whether they do the same in people is not known. Researchers have not been able to determine whether the rat findings apply to humans at all, and the warning reflects that uncertainty rather than proven harm.

Tell us right away if you notice a lump or swelling in your neck, hoarseness that will not clear, trouble swallowing, or shortness of breath. These can signal a thyroid problem and we will want to look.

Who should not take these medications

Do not take semaglutide or tirzepatide if you or a family member has had medullary thyroid carcinoma, a type of thyroid cancer.

The same applies if you have Multiple Endocrine Neoplasia syndrome type 2, usually written MEN 2. This inherited condition raises your risk of certain endocrine tumors. It is why we ask about your family history in more detail than you might expect.

You also should not take these drugs if you have had a serious allergic reaction to them before.

Allergic reactions and other risks

Serious allergic reactions, including anaphylaxis and swelling of the face or throat, have been reported since these drugs reached the market. If your face or throat swells, or you have trouble breathing, stop the medication and get help immediately.

We also screen for pancreatitis, gallbladder disease, and kidney trouble from dehydration. If you have diabetes and take insulin or a sulfonylurea, your blood sugar can drop too low, so we usually adjust those doses when you start.

None of this is a reason to be afraid of treatment. It is a reason to make sure you use a good doctor.

Cost, access, and considerations

The brand-name GLP-1 and dual-agonist drugs are expensive, and coverage for weight management varies enormously from plan to plan. Some cover them fully. Some exclude them outright. See our weight-loss medication insurance guide, plus deep dives on Virginia Medicaid and COVA and appealing a denial or paying cash.

Our team verifies your benefits, explains what you would actually pay, and walks through financing if you need it.

Next steps: schedule a medical weight-loss visit

The right medication depends on your history, your insurance, and what you are trying to achieve. Request a consultation and we will go through the options with you and start whichever one fits. For patients who need larger or more durable weight loss than medication alone delivers, Dr. Fitzer can also discuss gastric sleeve surgery (sleeve gastrectomy) as a complementary or alternative option.

Additional Reading

Read Dr. Fitzer's articles about Weight Loss Medications: Introduction for more information.

• Weight Regain After Wegovy/Zepbound Treatment?—Part 3
• Weight Regain After Wegovy/Zepbound Treatment?—Part 2
• Weight Regain After Wegovy/Zepbound Treatment?—Part 1
• Will I Regain when I stop Wegovy/Zepbound?
• Wegovy vs. Surgery Outcomes