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Retatrutide treatment
at Revival Clinic Bangkok

The Evolution of the "Gorilla": The Retatrutide Story

It is the world’s first Triple-Hormone Receptor Agonist. While previous medications only targeted one or two pathways, Retatrutide targets the "Triple G" Pathway:

  1. GLP-1: Controls hunger and slows digestion.

  2. GIP: Improves fat and sugar metabolism.

  3. Glucagon: The "secret weapon" that actually increases your body's energy expenditure (calorie burning), even while at rest.

Retatrutide Administration & Titration Guide

How to Administer

  • Route: Subcutaneous injection (SC).

  • Injection Sites: Abdomen, thigh, or upper arm.

  • Frequency: Once a week, at any time of day, with or without meals.

Retatrutide Titration Schedule 

To ensure patient safety and tolerability, the dose is gradually increased every 4 weeks. This "Start Low, Go Slow" approach allows the body to adapt to the metabolic changes. The primary objective of the titration schedule is to maximize weight loss while minimizing gastrointestinal side effects.

Month
sterile water to add in vial
weekly dose
Injection Volumn
Month 1
1 ml
1 mg
25 UNIT
Month 2
1 ml
2 mg
50 UNIT
Month 3
1 ml
3 mg
75 UNIT
Month 4
1 ml
4 mg
100 UNIT

Find your  " sweet spot " 

In our clinic, we don't believe in "one size fits all." We use a Data-Driven Personalized Approach to find your specific "Sweet Spot." This is the dose where your weight loss is consistent, but your quality of life remains high.​

We identify your Sweet Spot by monitoring 2  key indicators:​

  1. Appetite Neutrality (The Noise Test): The goal is to reach a state of "Food Neutrality"—where "food noise" (constant cravings) is gone, but you can still enjoy a healthy meal with friends. If you feel "too full" to eat or experience food aversion, we have likely passed your sweet spot.

  2. Side Effect Threshold: Research in The New England Journal of Medicine shows that gastrointestinal side effects and heart rate increases are "dose-dependent." If a patient experiences significant nausea at 8 mg but felt excellent at 4 mg with steady weight loss, we prioritize safety over speed and maintain the 4 mg dose.

"Our goal isn't the highest dose; it's the lowest dose that keeps you healthy, happy, and losing weight."

Why 4 mg is often the "Goldilocks" Dose

For the "non-obese but struggling" patient group, 4 mg often becomes the Sweet Spot. According to the NEJM (2023) Phase 2 data:

  • Efficiency: Participants on 4 mg lost approximately 17% of their body weight.

  • Liver Health: It provided a massive 57% reduction in liver fat, which is a primary health win for most patients.

  • Tolerability: It avoids the higher incidence of heart rate spikes and severe GI distress seen at the 12 mg maximum dose.

​

  • Jastreboff, A. M., et al. (2023). "Triple–Hormone-Receptor Agonist Retatrutide for Obesity — A Phase 2 Trial." The New England Journal of Medicine. (Evidence of dose-dependent efficacy and the 17% weight loss at 4 mg).

  • Sanyal, A. J., et al. (2024). "Retatrutide in Patients with NAFLD: A Randomized Phase 2 Trial." Hepatology/AASLD.(Confirms that lower doses are highly effective for metabolic/liver health).

  • Heise, T., et al. (2023). "Pharmacokinetics and Pharmacodynamics of Retatrutide." Diabetes, Obesity and Metabolism. (Highlights how the body processes the medication at various dose levels).

Hand Holding Syringe

How to Administer Your Injection: A Step-by-Step Guide

What you receive from us

  •  We prepare the whole set for you (vial + diluent + syringes/needles + alcohol swabs + instructions)

  •  Included syringes: (your planned number of injections) + 2 extra

  •  Need more supplies? You can buy more: 20 THB per injection set

One-time mixing (Reconstitution) — Do this once per vial

  1. Wash hands well with soap and water.

  2. Prepare a clean surface. Lay out:

    • Retatrutide vial (powder)

    • Diluent vial (as provided by clinic)

    • 1 syringe + needle

    • Alcohol swabs

  3. Swab both vial tops with alcohol. Let dry 10 seconds.

  4. Draw air into the syringe equal to the diluent amount on your clinic label.

  5. Inject the air into the diluent vial, then draw the diluent into the syringe.

  6. Insert needle into the retatrutide powder vial and slowly inject diluent down the inside wall of the vial (not blasting directly onto the powder).

  7. Gently swirl until clear. 

    • Do not shake.

  8. Label the vial with date/time mixed.

  9. Store in the refrigerator (2–8°C).

    • Do not freeze.

    • Keep away from light.

​

Each injection (SC) — Do this every time you inject

1) Prepare

  1. Take vial from fridge.

  2. Wash hands.

  3. Choose injection site:

    • Abdomen (best; avoid 2–3 cm around the navel)

    • Thigh (outer front)

    • Upper arm (back/outer area) if someone helps

  4. Rotate sites each time (avoid injecting the exact same spot).

2) Draw up the dose

  1. Swab vial top with alcohol; let dry.

  2. Draw air into syringe equal to your prescribed volume/units.

  3. Inject air into vial, turn vial upside down, and draw the prescribed units.

  4. Tap out bubbles and re-check the correct units.

3) Inject

  1. Clean skin with alcohol swab; let dry.

  2. Pinch a small fold of skin.

  3. Insert needle:

  • 90° for short insulin needles (4–6 mm)

  • 45° if very lean

  1. Inject slowly and steadily.

  2. Wait 2–3 seconds, then remove needle straight out.

  3. Press lightly with clean tissue/cotton (don’t rub).

4) Dispose safely

  1. Put used syringe/needle into a sharps container (or hard plastic bottle with lid).

  2. Never reuse needles.

Retatrutide — Who Should NOT Use It

Contraindications

(Based on Research & Trial Exclusions)

1) Personal/family history of medullary thyroid carcinoma (MTC) or MEN2

  • Similar medications in the GLP-1 receptor agonist class list this as a contraindication due to observed thyroid C-cell tumors in rodent studies and exclusion from trials.

  • Retatrutide trials have excluded people with such histories. 

Implication: If you or your family have a history of MTC or multiple endocrine neoplasia type 2, retatrutide is not recommended.

​

2) History of pancreatitis

  • Trials for related drugs often exclude individuals with pancreatitis due to possible risk of pancreatic inflammation.

  • While causal risk is debated, it remains a safety concern. 

Implication: Past pancreatitis → avoid until more safety data is available.

​

3) Baseline or recurrent severe hypoglycemia

  • Retatrutide lowers blood glucose. Individuals with baseline hypoglycemia or conditions predisposing to severe hypoglycemia are contraindicated. 

Implication: T1 diabetes or severe hypoglycemia risk conditions → contraindicated.

​

4) Pregnancy and breastfeeding

  • Because safety has not been established, retatrutide is not recommended for pregnant or breastfeeding individuals.

  • This aligns with typical practice for unapproved or investigational metabolic drugs. 

5) Pediatrics (<18 years)

  • Retatrutide trials focus exclusively on adults; safety in children/adolescents is unknown. 

Implication: Not for pediatric use.

​

âš  Precautions — Not Formal Contraindications, But Important

These are situations of concern based on safety patterns and class effects, pending more evidence:

• Severe gastrointestinal disease

Retatrutide can cause nausea, vomiting, diarrhea, constipation. Severe GI disease was often excluded in trials. 

• Gallbladder disease

GLP-1-related drugs have been associated with gallbladder issues; severe disease warrants caution. 

• Interactions with hypoglycemic medications

Using retatrutide with insulin or sulfonylureas increases risk of hypoglycemia; careful monitoring needed. 

• Cardiovascular conditions

Some patients in trials showed changes in heart rate; cardiovascular status should be reviewed before use. 

• Drug interactions

Drugs affecting GI motility or metabolism (e.g., motility agents, warfarin) may need monitoring. 

​

  • Retatrutide Clinical Trial Exclusion Criteria — ClinicalTrials.gov (family/personal history of MTC/MEN-2, pancreatitis, diabetes exclusions). 

  • Phase II Retatrutide Safety Findings — common GI side effects and safety profile. 

  • GLP-1 Contraindications: Thyroid Cancer and MEN-2 Risk — British Thyroid Foundation guidance for GLP-1-related drugs. 

  • Pancreatitis Risk and Safety with GLP-1 Receptor Agonists — FDA-related published safety concerns. 

  • Retatrutide Adult-Only Safety Data — retatrutide not studied in children. 

  • Regulatory Status and Lack of Formal Contraindications — current scientific review. 

Common Side Effects of Retatrutide

Retatrutide has shown promising results in clinical research for weight loss, but like all medications, it can cause side effects. Most are mild to moderate and often occur during the first weeks of treatment.

 Most Common Side Effects

These are the side effects most frequently reported in clinical studies:

  • Nausea (feeling sick)

  • Vomiting

  • Diarrhoea

  • Constipation

  • Abdominal discomfort or bloating

  • Decreased appetite

  • Fatigue or mild tiredness

  • Headaches

These effects are similar to those seen with other weight-loss injections that act on gut hormones and are typically digestive (gastrointestinal) symptoms. Many people find that side effects lessen over time as the body adjusts. 

References

  1. Jastreboff AM, et al. Triple–Hormone-Receptor Agonist Retatrutide for Obesity — Most frequent side effects were gastrointestinal symptoms like nausea, vomiting, diarrhoea, and constipation. New England Journal of Medicine.
    https://www.nejm.org/doi/full/10.1056/NEJMoa2301972

  2. Retatrutide side effects: what the research says so far — GI side effects such as nausea, vomiting, diarrhea, constipation, bloating, and abdominal pain reported.
    https://oviva.com/uk/en/retatrutide-side-effects/

  3. Retatrutide Side Effects: Safety and Management Guide — Nausea, vomiting, constipation, fatigue, diarrhea, headaches and abdominal discomfort are common.
    https://www.nicerx.com/blog/retatrutide-side-effects/

Retatrutide: Drug Interactions

Research shows it can affect other medicines mainly in two ways:

  1. changing how fast the stomach empties (which can affect absorption of some oral pills), and

  2. lowering blood sugar (which can interact with diabetes medicines).

​

1) Medicines that can cause low blood sugar (Hypoglycemia)

Retatrutide can lower blood sugar. If used with medicines that also lower sugar, the risk of hypoglycemia increases, especially with:

  • Insulin

  • Sulfonylureas (e.g., glipizide, gliclazide, glimepiride)

If you use any of these, your clinician may want closer monitoring. 
Reference link: https://www.nejm.org/doi/full/10.1056/NEJMoa2301972

2) Oral medications that may be affected by slower digestion

Retatrutide (like GLP-1–based medicines) can delay gastric emptying—meaning food and pills may move more slowly from the stomach into the intestine. This can delay or change absorption for some oral drugs, especially ones where timing matters.

Examples where extra caution is commonly advised (based on GLP-1 class evidence and expert reviews):

  • Oral contraceptive pills (birth control pills) — concern that effectiveness may be reduced around initiation/dose escalation due to delayed absorption (this has been noted with similar drugs and discussed for retatrutide as a potential issue). 
    Reference link: https://pmc.ncbi.nlm.nih.gov/articles/PMC11536522/

  • Levothyroxine (thyroid hormone) — oral semaglutide label reports increased levothyroxine exposure; this highlights why “narrow-window” meds may need monitoring when gastric emptying is affected. 
    Reference link (FDA label PDF): https://www.accessdata.fda.gov/drugsatfda_docs/label/2022/213051s011lbl.pdf

  • Other “narrow therapeutic index” medicines (where small changes in absorption can matter) may warrant extra attention depending on the patient (examples often discussed for the GLP-1 class include warfarin or digoxin—monitoring decisions should be individualized). 

  1. Jastreboff AM, et al. Triple–Hormone-Receptor Agonist Retatrutide for Obesity. NEJM (2023). 
    https://www.nejm.org/doi/full/10.1056/NEJMoa2301972

  2. Urva S, et al. Retatrutide delays gastric emptying (phase 1b / human data). Diabetes, Obesity and Metabolism(2023). 
    https://dom-pubs.onlinelibrary.wiley.com/doi/full/10.1111/dom.15167

  3. Deravi M, et al. Commentary/review noting potential interaction concerns (e.g., oral contraceptives) via delayed gastric emptying. (Review/Commentary, 2024)
    https://pmc.ncbi.nlm.nih.gov/articles/PMC11536522/

  4. FDA Label (example of GLP-1 class interaction mechanism): Rybelsus (oral semaglutide) — delayed gastric emptying may affect oral meds; levothyroxine exposure change reported. 
    https://www.accessdata.fda.gov/drugsatfda_docs/label/2022/213051s011lbl.pdf

  5. Shankar A, et al. GLP-1 receptor agonists and delayed gastric emptying (mechanism review). (2024)
    https://pmc.ncbi.nlm.nih.gov/articles/PMC11620716/

What if I want to stop Retatrutide? How should I stop it?

Retatrutide should not be stopped suddenly. In most cases, a gradual dose reduction (tapering) is recommended to help the body adjust and reduce the risk of increased appetite or weight regain. Always discuss your plan with your clinician, who can tailor the taper based on your current dose and how long you have been on treatment.

​

Example tapering approach (for guidance only):
If you are on a higher weekly dose, your clinician may reduce the dose step-by-step over several weeks, such as lowering the dose every 1–2 weeks (for example, from a higher dose to a mid dose, then to a lower dose) before stopping completely. The exact schedule will depend on your individual response and treatment goals.

​

Example tapering schedule (for guidance only):
If you are taking 4 mg once weekly:

  • Weeks 1–2: reduce to 3 mg once weekly

  • Weeks 3–4: reduce to 2 mg once weekly

  • Weeks 5–6: reduce to 1 mg once weekly

  • Then stop treatment

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