Zepbound and Mounjaro (tirzepatide): uses, side effects and cost in Puerto Rico

Zepbound is a brand name for tirzepatide, an Eli Lilly medicine injected under the skin once a week. It activates the receptors for two gut hormones at once, GIP and GLP-1. It helps your body release insulin when blood sugar rises, slows how fast your stomach empties and lowers appetite.

Per its FDA label, Zepbound is used with a reduced-calorie diet and more physical activity to reduce excess body weight and keep it off long term in adults with obesity, or adults with overweight and at least one weight-related condition such as high blood pressure, high cholesterol or prediabetes. It is also approved for moderate to severe obstructive sleep apnea in adults with obesity. It is not approved for children.

The dose starts at 2.5 mg a week and goes up in 2.5 mg steps no sooner than every 4 weeks, to help your stomach adjust. The 2.5 mg dose is only a starting dose; maintenance doses are 5, 10 or 15 mg.

Zepbound and Mounjaro contain the same active ingredient, tirzepatide, in the same doses, but the FDA approved them for different uses:

• Mounjaro: type 2 diabetes, in adults and children 10 and older, alongside diet and exercise; it is also approved to reduce the risk of heart attack, stroke or cardiovascular death in adults with type 2 diabetes and high cardiovascular risk.
• Zepbound: chronic weight management in adults, and obstructive sleep apnea with obesity.

Zepbound comes in single-dose pens, single-dose and multi-dose vials, and a 4-dose KwikPen. The label says not to combine tirzepatide with another tirzepatide product or any other GLP-1 medicine, such as semaglutide or Trulicity.

Many people search for Mounjaro for weight loss. Mounjaro is approved for diabetes, so if you do not have diabetes, using it to lose weight is off-label. The tirzepatide product approved for weight management is Zepbound.

If you have type 2 diabetes and overweight, Mounjaro can help with both, since weight loss is a known effect. If you have fatty liver, PCOS or prediabetes, the doctor takes that into account.

Before any medicine, the evaluation covers your weight and BMI, your health conditions, the medicines you take and any family history of thyroid cancer. If needed, we give you an order for lab tests at a lab near you (for example A1c, kidney function and cholesterol).

In the SURMOUNT-1 trial (NEJM, 2022), 2,539 adults with obesity, or overweight with a related condition and no diabetes, took tirzepatide or placebo for 72 weeks alongside diet and activity. Average weight change was -15.0% on 5 mg, -19.5% on 10 mg and -20.9% on 15 mg, versus -3.1% on placebo.

These are trial averages, not a promise: people respond differently, and some lose much less. The most common side effects were digestive, mostly mild to moderate, and happened mainly while the dose was going up.

In SURMOUNT-4 (JAMA, 2024), people who stopped tirzepatide after 36 weeks saw their body weight go up by an average of 14% over the next year, while those who stayed on it lost another 5.5%. That is why it is treated as a long-term medicine.

Per the Zepbound label, the most common side effects are nausea, diarrhea, vomiting, constipation, belly pain, indigestion, injection-site reactions, fatigue, burping, hair loss and reflux. They tend to be strongest when you start and each time the dose goes up.

Boxed warning (thyroid): in rats, tirzepatide caused thyroid C-cell tumors; it is not known whether this happens in people. It is not used if you or a family member has had medullary thyroid carcinoma (MTC), or if you have multiple endocrine neoplasia syndrome type 2 (MEN 2). Tell your doctor about a lump in your neck, trouble swallowing, shortness of breath or hoarseness that does not go away.

Other label warnings:

Tirzepatide can make birth control pills less effective. The label says to switch to a non-oral method, or add a barrier method such as condoms for 4 weeks after starting and for 4 weeks after each dose increase. Non-oral methods (shot, patch, ring, implant or IUD) should not be affected.

Pregnancy: weight loss offers no benefit during pregnancy and may harm the baby. If you become pregnant, stop Zepbound and tell your doctor. If you use Mounjaro for diabetes and become pregnant or plan a pregnancy, talk to your doctor before making changes. To review your method, see birth control by video.

What Zepbound and Mounjaro cost depends on the form, the dose, the pharmacy and whether your health plan covers it. If you have type 2 diabetes, ask your plan whether it covers Mounjaro; coverage for weight-loss medicines varies too.

For self-pay patients, Eli Lilly’s Zepbound savings page (checked October 9, 2026) lists a self-pay price starting at US$299 for one month of the 2.5 mg starting dose, as a KwikPen or vials; higher doses cost more, and the program requires you to be 18 or older and live in the United States or Puerto Rico. Prices change, so confirm before you buy.

The medicine is paid for separately from the visit. The clinic does not bill insurance; if you need one, we give you an itemized receipt for the visit for your claim.

Compounded tirzepatide is not FDA-approved: the agency does not review compounded drugs for safety, effectiveness or quality before they are sold. The FDA declared the tirzepatide shortage resolved in December 2024. The clinic does not prescribe compounded tirzepatide; it only prescribes FDA-approved brand medicines when they are appropriate for you.

Call 911 or go to an emergency room for severe belly pain that will not go away, signs of a serious allergic reaction (swelling of the face or throat, trouble breathing), vomiting or diarrhea that will not stop with dizziness or very little urine, or low blood sugar with confusion or fainting. See also when to go to the ER.