Zepbound is a once-weekly injection that contains tirzepatide. Adults use it, together with a reduced-calorie diet and more physical activity, to lose excess weight and keep it off. It is also approved for moderate to severe obstructive sleep apnea in adults with obesity. This guide explains what the current U.S. label says about uses, dosing patterns, side effects, birth control, and safety.
The facts below come mainly from the current Zepbound prescribing information on the FDA website (revised August 2026). Labels change over time, so check the newest version and the Medication Guide that comes with your prescription.
What Is Zepbound?
Zepbound is a brand-name prescription medicine from Eli Lilly. Its active ingredient, tirzepatide, activates two hormone receptors: GIP (glucose-dependent insulinotropic polypeptide) and GLP-1 (glucagon-like peptide-1). Both receptors sit in areas of the brain involved in appetite. The label gives tirzepatide’s half-life as about 5 to 6 days, which supports one injection per week.
You need a prescription. The label says to use Zepbound with a reduced-calorie diet and increased physical activity, not in place of them.
Zepbound and Mounjaro
Mounjaro is another brand of tirzepatide. Doctors prescribe it for type 2 diabetes. The two brands have separate labels, different approved uses, and separate instructions, so do not assume that advice for one applies to the other. The Zepbound label says not to use it with other tirzepatide products or with any GLP-1 medicine.
What Is Zepbound Used For?
The current label lists two approved uses, both for adults and both alongside diet and activity changes:
- Weight reduction and maintenance. It helps adults with obesity, or adults with overweight and at least one weight-related condition such as high blood pressure, abnormal cholesterol, sleep apnea, or heart disease, lose excess weight and maintain the loss long term.
- Obstructive sleep apnea (OSA). It treats moderate to severe OSA in adults with obesity. OSA is a condition in which breathing repeatedly pauses during sleep.
The label says doctors have not established safety and effectiveness in children.
How Much Weight Do People Lose?
Trial results show group averages, not promises. In a 72-week trial of adults with obesity or overweight and without diabetes, average weight 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 adults who also had type 2 diabetes, average loss was 12.8% on 10 mg and 14.7% on 15 mg, versus 3.2% on placebo. At least 5% weight loss occurred in 85% to 91% of people without diabetes who took Zepbound, compared with 34.5% on placebo.
The label also describes what happened when people stopped. In a withdrawal trial, adults who lost weight on Zepbound for 36 weeks were then assigned to keep taking it or switch to placebo. Over the next 52 weeks, the placebo group regained an average of 14.0% of body weight, while the Zepbound group lost a further 5.5%. Talk with your prescriber about long-term plans before you start.
Sleep Apnea Results
In two 52-week trials, adults taking 10 mg or 15 mg had average drops in the apnea-hypopnea index (AHI, the number of breathing pauses per hour) of about 25 to 29 events per hour, compared with about 5 on placebo. Remission or mild, non-symptomatic OSA occurred in 42.2% to 50.2% of Zepbound users versus 14.3% to 15.9% on placebo. The label notes the trials did not study when it is appropriate to stop CPAP (continuous positive airway pressure) therapy, so do not stop CPAP without your sleep doctor’s advice.
How Does Zepbound Work?
Tirzepatide lowers body weight, with more fat loss than lean mass loss. The label says it decreases calorie intake and likely works by affecting appetite. Animal studies show it reaches and activates brain regions that regulate appetite. It also boosts insulin release when blood sugar is high and lowers glucagon, a hormone that raises blood sugar. In addition, it slows stomach emptying. That slowing is strongest after the first dose and fades over time, which matters for birth control pills and anesthesia.
Zepbound Forms and Strengths
The label lists these presentations:
- Single-dose pens and single-dose vials: 2.5, 5, 7.5, 10, 12.5, or 15 mg in 0.5 mL.
- Multi-dose vials: four weekly doses; you draw each dose into a syringe.
- KwikPen: a single-patient-use pen with four fixed weekly doses.
Check the carton at each refill, and make sure you receive training for the exact presentation you get.
How to Use Zepbound Safely
Dosing Basics
Your prescriber sets your dose. For general understanding, the label describes this pattern:
- Start at 2.5 mg once weekly for 4 weeks. The label states this dose is for starting treatment and is not approved as a maintenance dose.
- Then move to 5 mg once weekly. After at least 4 weeks on a dose, the prescriber may raise it in 2.5 mg steps.
- For weight management, the maintenance dose is 5 mg, 10 mg, or 15 mg once weekly. For sleep apnea, it is 10 mg or 15 mg once weekly.
- The maximum is 15 mg once weekly. If you do not tolerate a maintenance dose, the label says your prescriber may consider a lower one.
Do not use this list to set your own dose.
Injecting Zepbound
- Inject once a week, at any time of day, with or without food.
- Inject under the skin of the abdomen or thigh. Another person can inject into the back of your upper arm. Never inject into a muscle or vein.
- Rotate the injection site each week.
- The liquid should be clear and colorless to slightly yellow, with no particles. Do not use it if it froze.
- Use a new needle and syringe for every injection with vials.
- Never share a KwikPen or needles, even if you change the needle.
People who are blind or have vision problems should not use the KwikPen without help from a trained person. The KwikPen needs priming before every injection, and you must throw it away after four weekly doses, even if liquid remains.
What to Do If You Miss a Dose
Take the missed dose as soon as possible within 4 days (96 hours) after it was due. If more than 4 days have passed, skip it and take your next dose on the regular day. Never take two doses within 3 days (72 hours) of each other. You may change your injection day if at least 3 days separate the two doses.
Common Side Effects of Zepbound
Digestive problems are the most common. In two 72-week weight-management trials, these effects happened more often with Zepbound than with placebo:
| Side effect | Placebo | 5 mg | 10 mg | 15 mg |
|---|---|---|---|---|
| Nausea | 8% | 25% | 29% | 28% |
| Diarrhea | 8% | 19% | 21% | 23% |
| Vomiting | 2% | 8% | 11% | 13% |
| Constipation | 5% | 17% | 14% | 11% |
| Abdominal pain | 5% | 9% | 9% | 10% |
| Dyspepsia (indigestion) | 4% | 9% | 9% | 10% |
| Injection site reactions | 2% | 6% | 8% | 8% |
| Fatigue | 3% | 5% | 6% | 7% |
| Hair loss | 1% | 5% | 4% | 5% |
Overall, 56% of people on Zepbound had a digestive reaction, versus 30% on placebo. The label says most nausea, vomiting, and diarrhea happened during dose increases and eased over time. Between 4.8% and 6.7% of people stopped Zepbound because of side effects, compared with 3.4% on placebo.
The label also lists hair loss, which it links to weight loss. It was more common in women (7.1%) than in men (0.5%) in the trials. Other findings include allergic-type reactions (mostly rash and itching), belching, heartburn, low blood pressure (1.6% versus 0.1%), a small rise in resting heart rate of 1 to 3 beats per minute, and dry mouth.
Serious Side Effects and Warnings
Boxed Warning: Thyroid C-Cell Tumors
Zepbound carries the FDA’s strongest warning. In rats, tirzepatide caused thyroid C-cell tumors. No one knows whether it causes these tumors, including a rare cancer called medullary thyroid carcinoma (MTC), in people. Do not use Zepbound if you or a family member has had MTC, or if you have Multiple Endocrine Neoplasia syndrome type 2 (MEN 2). Report a neck lump, trouble swallowing, shortness of breath, or lasting hoarseness.
Other Important Warnings
- Severe stomach problems. Severe digestive reactions affected 1.7% to 3.1% of Zepbound users and 1% of placebo users. The label does not recommend Zepbound in people with severe gastroparesis (very slow stomach emptying).
- Kidney injury. Vomiting and diarrhea can dehydrate you and injure the kidneys. Some people needed dialysis.
- Gallbladder disease. Gallbladder inflammation affected 0.7% of Zepbound users versus 0.2% on placebo. The label links these events to weight loss.
- Pancreatitis. Severe, persistent stomach pain, sometimes spreading to the back, calls for stopping the medicine and getting help right away.
- Allergic reactions. Swelling of the face, lips, tongue, or throat, trouble breathing, or severe rash needs emergency care.
- Low blood sugar. In adults with type 2 diabetes, it occurred in 4.2% versus 1.3% on placebo, and in 10.3% of those who also took a sulfonylurea. It has also been reported in people without diabetes.
- Diabetic eye disease. Rapid blood sugar improvement can temporarily worsen retinopathy in people with type 2 diabetes. Report vision changes.
- Anesthesia and sedation. Slower stomach emptying can leave food in the stomach even after fasting, and stomach contents can reach the lungs during anesthesia or deep sedation. Tell every surgeon, dentist, and anesthesia provider that you use Zepbound.
The February 2026 label update removed the separate warning section on suicidal behavior and ideation. Even so, tell your provider about any mood changes you notice during treatment.
Who Should Avoid Zepbound or Use Caution?
The label lists two contraindications: a personal or family history of MTC or MEN 2, and a known serious allergic reaction to tirzepatide or any ingredient. Tell your prescriber before you start if you have had pancreas problems, severe stomach or digestion problems, diabetic eye disease, or a planned procedure that uses anesthesia.
The label found no overall differences in safety or effectiveness in adults 65 and older, although few people aged 75 and older took part. It recommends no dose change for kidney or liver impairment, but it advises monitoring kidney function in people who have vomiting or diarrhea.
Zepbound, Birth Control, and Other Drug Interactions
Zepbound can reduce how well birth control pills work. Because it slows stomach emptying, it can lower absorption of the pill’s hormones. The label tells people who use oral hormonal contraceptives to switch to a non-oral method or add a barrier method (such as condoms) for 4 weeks after starting Zepbound and for 4 weeks after each dose increase. Hormonal contraceptives that are not taken by mouth should not be affected.
The slower emptying can also affect other pills. The label advises monitoring people who take oral medicines that depend on reaching a threshold level, or that have a narrow safety margin, such as warfarin. After the first dose, peak acetaminophen levels dropped by 55%, but the effect was not meaningful by week 6. If you use insulin or a sulfonylurea, ask your prescriber about lowering those doses to prevent low blood sugar.
Pregnancy and Breastfeeding
Pregnancy. The label says weight loss offers no benefit during pregnancy and may cause fetal harm. Stop Zepbound when you learn you are pregnant. Animal studies showed possible harm to the fetus, and a pregnancy exposure registry will track outcomes. Keep in mind the birth control warning above, and ask your doctor about planning before you try to conceive.
Breastfeeding. In a study of 11 breastfeeding women, tirzepatide was undetectable or very low in breast milk. No data exist on effects on the baby or milk production. Discuss the benefits of breastfeeding and your treatment needs with your provider.
How to Store Zepbound
- Keep it in the original carton, away from heat and light. Do not freeze it, and do not use it if it froze.
- Single-dose pens and vials: Refrigerate at 36°F to 46°F (2°C to 8°C). If needed, you can keep them at up to 86°F (30°C) for a total of 21 days, then discard them.
- Multi-dose vials and KwikPens, unopened: Refrigerate. At room temperature, discard unopened products after 30 days.
- Multi-dose vials and KwikPens, in use: Keep in the carton, in the refrigerator or at room temperature up to 86°F. Discard after 30 days at room temperature, 30 days after first use, or after four weekly doses.
Counterfeit and Compounded Tirzepatide
High demand has created a market for unapproved copies. The FDA states that compounded GLP-1 drugs, including tirzepatide products, are not FDA approved, and it has received reports of dosing errors, side effects, and fraudulent products. Use only prescriptions from licensed pharmacies, and report suspicious products to your pharmacist and to the FDA’s MedWatch program.
When to Get Medical Help
Call 911 or go to an emergency room for trouble breathing or swelling of the face, lips, tongue, or throat. Contact a healthcare provider promptly for severe or lasting stomach pain, repeated vomiting or diarrhea, signs of dehydration, a neck lump, vision changes, upper belly pain with fever or yellowing skin, or symptoms of low blood sugar such as shakiness, sweating, confusion, or a fast heartbeat. In case of an overdose, call Poison Help at 1-800-222-1222.
Frequently Asked Questions About Zepbound
Is Zepbound the same as Mounjaro?
Both contain tirzepatide, but they are separate brands with different approved uses. Zepbound is approved for weight management and sleep apnea. Mounjaro is approved for type 2 diabetes. Do not use them together.
Will I regain weight if I stop Zepbound?
In the label’s withdrawal trial, people who switched to placebo regained an average of 14.0% of body weight over 52 weeks. Your results may differ, so talk with your prescriber before you stop.
Can Zepbound treat sleep apnea on its own?
The label approves it for moderate to severe OSA in adults with obesity, and trials showed large drops in AHI. The trials did not study when to stop CPAP, so keep using CPAP unless your sleep doctor says otherwise.
Can I use Zepbound with birth control pills?
You can, but the pill may work less well. The label advises a non-oral or barrier method for 4 weeks after you start and 4 weeks after each dose increase.
Does Zepbound cause hair loss?
Hair loss was reported more often than with placebo, and the label links it to weight loss. It was more common in women. Tell your prescriber if it bothers you.
Can I share a pen with someone who has the same prescription?
Never. Sharing a KwikPen or needles can pass on serious blood-borne infections, even if you change the needle.
References
- Zepbound (tirzepatide) prescribing information, U.S. FDA (revised 08/2026)
- GLP-1 agonists, MedlinePlus Medical Encyclopedia
- FDA’s Concerns with Unapproved GLP-1 Drugs Used for Weight Loss
Conclusion
Zepbound is a once-weekly tirzepatide injection for long-term weight management and for moderate to severe sleep apnea in adults with obesity. Trials showed large average weight loss, but the label also describes weight regain after stopping, a boxed warning, and real risks, including digestive problems, gallbladder disease, pancreatitis, and dehydration. Follow your prescriber’s plan, plan around the birth control warning, tell every care provider before a procedure, and buy only genuine product from a licensed pharmacy.
Medical Disclaimer
Disclaimer: This article is for informational purposes only and does not constitute medical advice, diagnosis, or treatment. The information provided is not a substitute for professional medical advice from a qualified healthcare provider. Always consult your doctor or pharmacist before starting, stopping, or changing any medication. Do not disregard professional medical advice or delay seeking it because of information in this article. If you think you are experiencing a medical emergency, seek emergency medical assistance immediately.