Semaglutide vs Tirzepatide vs Retatrutide: Side Effects

    •By Trimi Medical Team•14 min read

    All GLP-1 medications share a similar core side effect profile (primarily gastrointestinal), but the severity, duration, and specific effects differ between semaglutide, tirzepatide, and retatrutide. Understanding these differences helps you choose the medication most likely to be tolerable for your body.

    Medical Disclaimer: This article is for informational purposes only and does not constitute medical advice. Side effects vary significantly between individuals. Report any concerning symptoms to your healthcare provider immediately.

    Side Effect Comparison Table

    Side EffectSemaglutideTirzepatideRetatrutide
    Nausea40-45%35-40%40-50%
    Vomiting15-20%10-15%15-20%
    Diarrhea25-30%15-20%25-30%
    Constipation15-20%15-20%15-20%
    Increased Heart RateMinimalMinimalModerate (glucagon)
    Feeling Warm/HotUncommonUncommonCommon (thermogenesis)
    Hair ThinningRelated to weight loss rateModerate-HighHigher
    Discontinuation Rate~5-7%~3-5%~5-8%

    Key Differences Explained

    Semaglutide: The Most-Studied Profile

    Semaglutide has the most long-term safety data (15+ years for the GLP-1 class). Its side effects are well-characterized and predominantly gastrointestinal. Most side effects improve within 4-8 weeks of each dose increase. Nausea tends to be worst during the first few days after each injection.

    Tirzepatide: Generally Best Tolerated

    Despite producing more weight loss, tirzepatide tends to have slightly lower nausea and vomiting rates than semaglutide in head-to-head comparisons. The GIP component may have a buffering effect on GLP-1-related nausea. Tirzepatide has the lowest discontinuation rate due to side effects among the three medications.

    Retatrutide: Unique Glucagon Effects

    Retatrutide's glucagon receptor activation introduces side effects not seen with semaglutide or tirzepatide. The increased thermogenesis can make patients feel warm or slightly flushed. A modest increase in resting heart rate (3-5 bpm) is common. GI side effects are comparable to semaglutide but with the added complexity of three-receptor activation.

    Managing Side Effects: Universal Strategies

    • Eat slowly and smaller portions: The most effective nausea prevention
    • Stay hydrated: Dehydration worsens every side effect
    • Ginger supplements: Clinically proven for GLP-1-related nausea
    • Titrate gradually: Do not rush dose increases
    • Time injections strategically: Some patients do better injecting in the evening

    Choose Your Best Fit with Trimi

    Trimi's medical team helps match you with the right medication for your tolerability. Compounded semaglutide is $99/month and compounded tirzepatide is $125/month. Visit our treatment page to start.

    Frequently Asked Questions

    Which GLP-1 has the fewest side effects?

    Tirzepatide has the lowest discontinuation rate due to side effects in clinical trials, making it the best-tolerated option overall. However, individual responses vary. Some patients tolerate semaglutide perfectly but struggle with tirzepatide, and vice versa.

    Do side effects get worse with stronger medications?

    Not necessarily. Side effects are primarily dose-dependent (higher doses = more side effects) rather than medication-dependent. Because all three medications start at low doses and titrate up, the side effect experience is similar during the early weeks regardless of which medication you choose.

    Can I switch to avoid specific side effects?

    Yes. If you have persistent side effects on one medication, switching to another GLP-1 may resolve them. The different receptor profiles mean your body may respond differently to each medication.

    More on 3-Way Comparisons

    View all 3-Way Comparisons articles

    Sem vs Tir vs Ret: Cost

    Price comparison of all three.

    Discuss Side Effects with Doctor

    How to communicate about side effects.

    Which GLP-1 Decision Framework

    Choosing the right medication.

    Sources & References

    1. Wilding JPH et al. Once-Weekly Semaglutide in Adults with Overweight or Obesity. NEJM 2021;384:989-1002.
    2. Jastreboff AM et al. Tirzepatide Once Weekly for the Treatment of Obesity. NEJM 2022;387:205-216.
    3. Lincoff AM et al. Semaglutide and Cardiovascular Outcomes in Obesity without Diabetes. NEJM 2023;389:2221-2232.
    4. FDA Prescribing Information for Wegovy (semaglutide) and Zepbound (tirzepatide).

    Related Reading

    What does the current clinical evidence support for GLP-1-based weight management?

    GLP-1 receptor agonists (semaglutide, tirzepatide) have Phase 3 RCT evidence for chronic weight management in adults with BMI ≥30 or BMI ≥27 with a weight-related comorbidity. Trimi offers compounded preparations of the same active ingredients at $99/month (semaglutide) and $125/month (tirzepatide) on the annual plan, prepared per individual prescription by 503A community sterile compounding pharmacies and reviewed by a US-licensed clinician through Beluga Health's 50-state physician network. Compounded preparations are not themselves FDA-approved as drugs; the active ingredients are FDA-approved in the corresponding brand finished products. Eligibility is determined by a licensed clinician.

    Phase 3 RCT evidence base: STEP 1 (NEJM 2021), SURMOUNT-1 (NEJM 2022), SELECT (NEJM 2023), FLOW (NEJM 2024)
    Trimi pricing: $99/month semaglutide / $125/month tirzepatide on annual plan
    Clinical review: Dr. Asad Niazi, MD MPH via Beluga Health 50-state network

    Key Takeaways

    • Compounded semaglutide and compounded tirzepatide are prepared per individual prescription by 503A community sterile compounding pharmacies (VialsRx — Texas State Board pharmacy license #35264 — and GreenwichRx). The active ingredients (semaglutide, tirzepatide) are FDA-approved in the corresponding brand finished products (Wegovy / Ozempic and Zepbound / Mounjaro respectively). Compounded preparations are not themselves FDA-approved as drugs.
    • Eligibility for GLP-1 treatment is determined by a licensed clinician: BMI ≥30, or BMI ≥27 with at least one weight-related comorbidity (type 2 diabetes, hypertension, dyslipidemia, obstructive sleep apnea, cardiovascular disease). Contraindications include personal/family history of medullary thyroid carcinoma, MEN 2 syndrome, pancreatitis, severe gastrointestinal disease, severe renal impairment, pregnancy, and breastfeeding.
    • Common GLP-1 receptor agonist adverse effects include nausea, vomiting, diarrhea, constipation, and gallbladder events. Most are mild-to-moderate and concentrated during dose escalation. Severe gastrointestinal symptoms causing dehydration can increase acute kidney injury risk and should be reported to the prescribing clinician.
    • Trimi's clinical review is coordinated by Dr. Asad Niazi, MD MPH through Beluga Health's 50-state physician network. Trimi pricing: $99/month for compounded semaglutide and $125/month for compounded tirzepatide on the annual plan; flat across all prescribed doses within whichever plan, with no enrollment / consultation / shipping fees.
    • This is general information based on the cited sources, not medical advice. Treatment decisions require evaluation by a licensed clinician familiar with your individual medical history.

    Medically Reviewed

    TMRT

    Trimi Medical Review Team

    Clinical review workflow for GLP-1 safety, dosing, and access content

    Team-based medical review process documented in Trimi's Medical Review Policy

    Last reviewed: February 25, 2026

    TCCT

    Written by Trimi Clinical Content Team

    Medical Writers & Healthcare Professionals

    Our clinical content team includes registered nurses, pharmacists, and medical writers who specialize in translating complex medical information into clear, actionable guidance for patients.

    Medically reviewed by Trimi Medical Review Team, Clinical review workflow for GLP-1 safety, dosing, and access content

    What real Trimi patients say

    Verbatim quotes from Trimi's Facebook and Reddit community reviews. First name and last initial preserved per editorial policy.

    I'm on my 4th week. No side effects. 5 lb loss which seems slow to me. Food noise is much better. We shall see!

    Outcome: 5 lbs lost in 4 weeks; no side effects; food noise reduced

    — Lynn SchweitzerFacebook
    21 lbs down in 6 weeks! So happy I started with you guys!

    Outcome: 21 lbs lost in 6 weeks

    — Robyn Lynn CurtisFacebook
    See all community reviews →

    Editorial Standards

    Trimi publishes patient education using a medical-review workflow, source-based claim checks, and dated updates for fast-changing pricing, access, and safety topics.

    Review our Editorial Policy and Medical Review Policy for more details about sourcing, updates, and reviewer attribution.

    Scientific References

    1. Garvey WT, Mechanick JI, Brett EM, et al. (2024). American Association of Clinical Endocrinology / American College of Endocrinology Comprehensive Clinical Practice Guidelines for Medical Care of Patients with Obesity. Endocrine Practice.Read StudyDOI: 10.4158/EP161365.GL
    2. American Heart Association (2021). Obesity and Cardiovascular Disease: A Scientific Statement From the American Heart Association. Circulation.Read StudyDOI: 10.1161/CIR.0000000000000973
    3. Apovian CM, Aronne LJ, Bessesen DH, et al. (2015). Pharmacological Management of Obesity: An Endocrine Society Clinical Practice Guideline. Journal of Clinical Endocrinology & Metabolism.Read StudyDOI: 10.1210/jc.2014-3415

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