Question 1

What is the difference between Mounjaro and Zepbound?

Accepted Answer

Mounjaro and Zepbound contain the identical molecule — tirzepatide — manufactured by Eli Lilly. Mounjaro is approved for type 2 diabetes, while Zepbound is approved for chronic weight management in adults with obesity or overweight with at least one weight-related comorbidity. The dosing, delivery device, and available strengths are the same. The distinction is purely regulatory, affecting insurance coverage and prescribing indications.

Question 2

How much weight can I lose on tirzepatide?

Accepted Answer

In the SURMOUNT-1 clinical trial, average weight loss was 15.0% at 5mg, 19.5% at 10mg, and 20.9% at 15mg over 72 weeks. Individual results vary significantly — some participants lost over 25% of their body weight, while others lost less than 10%. Factors that influence response include starting BMI, adherence to dose titration, diet, physical activity, and individual metabolic factors.

Question 3

Is tirzepatide better than semaglutide?

Accepted Answer

In the only head-to-head trial (SURPASS-2), tirzepatide produced significantly greater weight loss and HbA1c reduction than semaglutide 1mg. However, this comparison used semaglutide at the diabetes dose, not the higher weight-management dose (2.4mg). Cross-trial comparisons suggest tirzepatide 15mg produces approximately 5-6 percentage points more weight loss than semaglutide 2.4mg, but direct head-to-head data at the obesity doses is lacking.

Question 4

How long does tirzepatide take to work?

Accepted Answer

Most patients begin noticing appetite changes within the first 1-2 weeks. Clinically meaningful weight loss (5% or more of body weight) typically occurs by weeks 8-12, though the dose-titration schedule means patients are still at lower doses during this period. Maximum weight loss generally occurs at 9-12 months of treatment at the maintenance dose.

Question 5

Can I get compounded tirzepatide?

Accepted Answer

Compounded tirzepatide is available from compounding pharmacies when the drug is listed on the FDA Drug Shortage List. Compounded versions are significantly less expensive than brand-name Mounjaro or Zepbound but carry greater quality variability. TriedRx tracks 136 vendors and 1,748 samples of compounded tirzepatide — check our vendor testing data for purity and potency information before selecting a supplier.

Question 6

What are the most common side effects of tirzepatide?

Accepted Answer

The most common side effects are gastrointestinal: nausea (24-33%), diarrhea (17-21%), vomiting (6-12%), constipation (6-11%), and decreased appetite (13-21%). These effects are most pronounced during dose escalation and typically improve at a stable dose. Approximately 4-7% of clinical trial participants discontinued due to adverse events. Serious but rare side effects include pancreatitis, gallbladder events, and injection site reactions.

Question 7

Does tirzepatide cause muscle loss?

Accepted Answer

Yes, approximately 30-35% of total weight lost with tirzepatide is lean mass (primarily muscle), based on body composition sub-study data. This is a concern across all GLP-1 agonists and weight-loss interventions generally. Resistance training at least 2-3 times per week and protein intake of 1.2-1.6g per kilogram of body weight per day are widely recommended to mitigate muscle loss during therapy.

Question 8

Can I take tirzepatide if I don't have diabetes?

Accepted Answer

Yes. Zepbound (tirzepatide) is FDA-approved specifically for chronic weight management in adults without diabetes who have a BMI of 30 or greater, or BMI of 27 or greater with at least one weight-related condition such as hypertension, dyslipidemia, or obstructive sleep apnea. You do not need to have diabetes to receive a prescription for tirzepatide for weight management.

#	Vendor	Avg score	Purity range	Tests	Verified $/mg	Grade	Profile
Grade B+ — Very Good
1	Polaris Peptides	8.8	98.4 – 99.6%	15	—	B+	review →
2	Aavant Research	8.7	98.1 – 99.3%	9	—	B+	review →
3	Shanghai JinBei Chemical	8.6	98.4 – 99.6%	9	—	B+	review →
4	Paradigm Peptide	8.4	98.2 – 99.4%	14	—	B+	review →
5	Zhejiang Yichenkang	8.2	97.9 – 99.1%	8	—	B+	review →
Grade C — Okay
6	Peptide Partners	8.2	98.4 – 99.6%	6	$2.40	C	review →

Vendor Rankings

Tirzepatide Rankings