What Are Tirzepatide Injections?
Tirzepatide injections are a once-weekly prescription medicine, injected under the skin, that activates the receptors for two gut hormones, GIP and GLP-1, to lower blood sugar and reduce appetite. Tirzepatide is sold as Mounjaro for type 2 diabetes and as Zepbound for weight management and obstructive sleep apnea.
Both are used along with diet and physical activity. Tirzepatide carries an FDA boxed warning because it caused thyroid C-cell tumors in rats. It is unknown whether it causes these tumors in people.
Tirzepatide Injections at a Glance
| Brand names | Mounjaro and Zepbound |
|---|---|
| Drug class | Dual GIP and GLP-1 receptor agonist (an incretin mimetic) |
| What it treats | Type 2 diabetes; obesity or overweight with a weight-related condition; moderate to severe obstructive sleep apnea in adults with obesity |
| How it's given | Injection under the skin of the abdomen, thigh or upper arm, once a week |
| How long it lasts | Half-life of about 5 days. Meant for long-term use. |
| Common side effects | Nausea, diarrhea, vomiting, constipation, stomach pain and indigestion |
| FDA status | FDA approved (first in 2022). Compounded versions are not FDA approved. |
What Are Tirzepatide Injections Used For?
Tirzepatide injections are FDA approved for three uses:
- Type 2 diabetes (Mounjaro): blood sugar control in adults and children 10 and older.
- Weight management (Zepbound): adults with obesity (a BMI of 30 or higher), or overweight plus at least one weight-related condition.
- Obstructive sleep apnea (Zepbound): the first drug approved, in December 2024, for moderate to severe sleep apnea in adults with obesity.
In the main weight-management trial, 2,539 adults without diabetes were treated for 72 weeks. Average weight loss was 15.0% at 5 mg, 19.5% at 10 mg and 20.9% at 15 mg, compared with 3.1% on placebo.
How Do Tirzepatide Injections Work?
Tirzepatide injections work by activating the receptors for two gut hormones, GIP and GLP-1. Both receptors are found in brain areas that regulate appetite. The result is lower calorie intake. Tirzepatide also stimulates insulin release when blood sugar is high, lowers glucagon, improves insulin sensitivity and slows stomach emptying. Weight lost on tirzepatide is more fat than lean mass.
How Are Tirzepatide Injections Taken?
Tirzepatide is injected under the skin once a week, at any time of day, with or without meals.
- Dose: treatment starts at 2.5 mg a week for 4 weeks, then rises in 2.5 mg steps no sooner than every 4 weeks. The maximum is 15 mg a week for adults and 10 mg a week for children taking Mounjaro.
- Where: the abdomen or thigh, or the back of the upper arm if someone else injects. Rotate sites each week.
- Missed dose: take it within 4 days, or skip it. Keep doses at least 3 days apart.
- Storage: refrigerate at 36 to 46°F. Single-dose pens or vials can stay at room temperature for up to 21 days.
What Are the Side Effects of Tirzepatide Injections?
The most common side effects of tirzepatide injections affect digestion, and most nausea, vomiting and diarrhea happen while the dose is being increased. Other common effects include injection-site reactions, fatigue, burping, hair loss and acid reflux.
Call your clinician right away for:
- Stomach pain that won't go away, sometimes spreading to the back (possible pancreatitis)
- Swelling of the face or throat, hives or trouble breathing
- A lump or swelling in the neck, hoarseness or trouble swallowing
- Vomiting or diarrhea severe enough to cause dehydration, which can harm the kidneys
- Low blood sugar, especially if you also take insulin or a sulfonylurea
Who Shouldn't Take Tirzepatide Injections?
Tirzepatide injections should not be used by people with a personal or family history of medullary thyroid carcinoma, people with multiple endocrine neoplasia syndrome type 2 (MEN 2), or anyone with a serious allergy to tirzepatide. Other FDA label warnings:
- Pregnancy: stop tirzepatide when pregnancy is recognized, because it may harm the baby.
- Birth control pills: switch to a non-oral method, or add a barrier method, for 4 weeks after starting and after each dose increase.
- Severe gastroparesis: tirzepatide is not recommended.
- Surgery or sedation: tell your clinicians before any planned surgery or procedure. Rare cases of stomach contents being inhaled into the lungs have been reported during general anesthesia or deep sedation.
Tirzepatide vs. Semaglutide
Tirzepatide and semaglutide both treat obesity and type 2 diabetes, but tirzepatide activates both GIP and GLP-1 receptors, while semaglutide activates only GLP-1 receptors.
| Tirzepatide | Semaglutide | |
|---|---|---|
| Hormone receptors | GIP and GLP-1 | GLP-1 only |
| Brand names | Mounjaro, Zepbound | Ozempic, Wegovy |
| How it's given | Weekly injection | Weekly injection (Wegovy). Wegovy also comes as a pill. |
| Head-to-head weight loss at 72 weeks | 20.2% | 13.7% |
| Other approved uses | Sleep apnea | Lowering heart risk in people with heart disease and overweight or obesity |
The American Diabetes Association advises choosing an obesity medicine based on goals, cost, access, tolerability, side-effect risk and personal preference.
Tirzepatide Injections at GENEVA
At GENEVA Primary Care & Med Spa in Alpharetta, GA, a provider evaluates whether tirzepatide is a good fit by reviewing your weight history, health conditions, medicines and family history. Your provider then recommends treatment at GENEVA or a referral to a specialist.
Learn more about tirzepatide injections for weight loss and GENEVA's medical weight loss program. GENEVA serves patients from Alpharetta, Johns Creek, Milton, Roswell and Cumming.
Related Terms
- Zepbound
- Mounjaro
- Tirzepatide titration schedule
- Dual GIP/GLP-1 agonist
- Compounded tirzepatide
- Semaglutide injections
- Body mass index (BMI)
Tirzepatide Injections FAQs
Are Mounjaro and Zepbound the same as tirzepatide?
Yes. Mounjaro and Zepbound both contain tirzepatide, but the FDA approved them for different uses. Mounjaro treats type 2 diabetes in adults and children 10 and older. Zepbound treats obesity, or overweight with at least one weight-related condition, in adults, and moderate to severe obstructive sleep apnea in adults with obesity. Both start at 2.5 mg a week, with a maximum adult dose of 15 mg. The Zepbound label advises against using it with other tirzepatide products or any GLP-1 receptor agonist, so don't combine the two.
How much weight can you lose on tirzepatide?
In the main clinical trial, adults without diabetes lost an average of 15.0% to 20.9% of their body weight over 72 weeks, depending on the dose, versus 3.1% on placebo. Adults with type 2 diabetes lost an average of 12.8% at 10 mg and 14.7% at 15 mg. Results vary, and some people don't lose weight on obesity medicines. The Obesity Medicine Association advises considering another option if weight loss is under 5% after 12 to 16 weeks at the highest tolerated dose.
What are the most common side effects of tirzepatide?
The most common side effects of tirzepatide are nausea, diarrhea, vomiting, constipation, stomach pain and indigestion. Most nausea, vomiting and diarrhea happens while the dose is being increased and eases over time. In the weight-management trials, digestive side effects affected 56% of people on tirzepatide versus 30% on placebo, and 1.9% to 4.3% stopped treatment because of them. Call your clinician right away for stomach pain that won't go away, a possible sign of pancreatitis, or for facial swelling or trouble breathing.
What happens when you stop taking tirzepatide?
Most people regain weight after stopping tirzepatide, so obesity specialists recommend a long-term treatment approach. In a withdrawal trial, adults lost an average of 20.9% of their body weight during 36 weeks on tirzepatide. People then switched to placebo saw their weight rise by an average of 14.0% over the next 52 weeks, while those who stayed on tirzepatide lost another 5.5%. Don't stop tirzepatide without talking to your clinician first.
Is tirzepatide better than semaglutide for weight loss?
In a head-to-head trial in adults with obesity, tirzepatide led to more weight loss than semaglutide: an average of 20.2% versus 13.7% after 72 weeks. The trial, SURMOUNT-5, enrolled 751 adults without type 2 diabetes and was funded by Eli Lilly, which makes tirzepatide. The most common side effects in both groups were digestive, and most were mild to moderate. Wegovy, a semaglutide brand, is approved to lower heart risk in people with heart disease and overweight or obesity, so the best choice depends on your health, goals and coverage.
Is compounded tirzepatide safe?
Compounded tirzepatide is not FDA approved, so the FDA has not reviewed its safety, effectiveness or quality. The FDA says compounded drugs should be used only when a patient's needs can't be met by an FDA-approved drug. As of May 31, 2026, the FDA had received more than 730 adverse event reports associated with compounded tirzepatide. The FDA is also aware of fraudulent compounded tirzepatide with false pharmacy information on the label. Fill prescriptions at a state-licensed pharmacy, and don't use an injection that arrives warm.
Can a primary care provider prescribe tirzepatide?
Yes. Tirzepatide is a prescription medicine, and a primary care provider can evaluate whether it suits you. For people with or at risk of diabetes, the American Diabetes Association recommends checking weight-related measurements at least every 3 months during active weight management. At GENEVA in Alpharetta, your provider reviews your weight history, health conditions, medicines and family history of thyroid cancer, then recommends either treatment at GENEVA or a referral to a specialist. Bring a list of all your medicines, since tirzepatide can affect how some pills are absorbed.