Key takeaways: switching from Wegovy to Mounjaro
- Different medicines: Wegovy is a GLP-1 injection. Mounjaro is a dual GIP and GLP-1 injection. Doses cannot be swapped one-for-one.
- Why people switch: Plateaus, side-effect differences, and stronger average trial results with tirzepatide in SURMOUNT-5 (20.2% vs 13.7% at 72 weeks).
- Existing patients: Switching patients at PrivateDoc need a BMI above 21 kg/m² and a current or recent course (within 12 months).
- Gap: Wait 7 days after the last Wegovy dose if side effects were none to moderate, or 14 days after severe gastrointestinal effects. Never overlap the two injections.
- Starting dose: High-dose Wegovy does not mean starting Mounjaro at 15 mg. Mapping depends on your current strength and how well you tolerated semaglutide.
Why consider switching from Wegovy to Mounjaro?
Dual GIP and GLP-1 action vs GLP-1 alone
Wegovy mimics GLP-1 to slow emptying and increase satiety. Mounjaro also targets GIP, which can further affect fat metabolism, insulin sensitivity, and food cravings.
Plateaus
In the SURMOUNT-5 trial, tirzepatide produced 20.2% average weight loss versus 13.7% with semaglutide over 72 weeks. If progress has stalled on a stable Wegovy dose (including 1.7 mg, 2.4 mg, or 7.2 mg), a clinician may consider Mounjaro.
Side-effect profile
Some people with persistent nausea or reflux on Wegovy feel better on Mounjaro. Others with severe Wegovy side effects need a cautious reset at a low tirzepatide dose.
Who can switch to Mounjaro?
Under PrivateDoc criteria, a switch is considered when:
- Recent treatment: You have an active weight-loss prescription or a verified gap of 12 months or less.
- BMI: Switching or returning patients who have already lost a substantial amount of weight can continue if BMI remains above 21 kg/m². New starters still need BMI 30 or more, or 27 with a weight-related condition.
- Safety: There must be no absolute contraindication to tirzepatide, including personal or family history of medullary thyroid carcinoma, MEN2, pregnancy, breastfeeding, or active pancreatitis.
- Informed consent: There is no single manufacturer protocol for switching molecules. Starting above the licensed 2.5 mg introduction dose is a joint clinical decision.
PrivateDoc dose conversion: Wegovy to Mounjaro
| Current Wegovy dose |
Side effects on Wegovy |
Gap after last Wegovy dose |
Starting Mounjaro dose |
| 0.25 mg and 0.5 mg |
None / mild |
7 days |
5 mg |
| Moderate |
7 days |
2.5 mg |
| Severe |
14 days |
2.5 mg |
| 1 mg |
None / mild |
7 days |
5 mg to 7.5 mg |
| Moderate |
7 days |
5 mg |
| Severe |
14 days |
2.5 mg |
| 1.7 mg |
None / mild |
7 days |
7.5 mg to 10 mg |
| Moderate |
7 days |
5 mg |
| Severe |
14 days |
2.5 mg |
| 2.4 mg |
None / mild |
7 days |
10 mg |
| Moderate |
7 days |
7.5 mg |
| Severe |
14 days |
2.5 mg |
| 7.2 mg |
None / mild |
7 days |
10 mg to 15 mg |
| Moderate |
7 days |
7.5 mg |
| Severe |
14 days |
2.5 mg |
Clinical note: Patients who tolerated Wegovy well do not always restart Mounjaro at 2.5 mg. High-dose Wegovy still does not justify jumping straight to 15 mg except where the matrix above allows it after 7.2 mg with good tolerability.
Understanding the washout gap between doses
- 7-day gap: If side effects were none, mild, or moderate, wait 7 days after your last Wegovy injection. That matches a normal weekly schedule.
- 14-day gap: After severe symptoms such as persistent vomiting or dehydration, wait 14 days. Semaglutide's half-life is about one week; a longer washout lowers overlap risk.
- Never overlap: Do not inject Wegovy and Mounjaro in the same week or alternate them. Combined active doses sharply increase gastrointestinal risk.
How the switching process works at PrivateDoc
- Consultation: Request Mounjaro through the online consultation. Confirm your current Wegovy dose, recent weight verification, and any adverse reactions.
- Clinical triage: A GMC-registered doctor or independent prescriber reviews your history against the conversion matrix. Unexplained severe side effects are discussed before any switch.
- Consent: If you may start above 2.5 mg, you receive a clinical acknowledgement covering stomach-related risks. The prescription is authorised only after you confirm.
- Timed first dose: Your Mounjaro KwikPen is sent from our UK pharmacy in temperature-controlled packaging. Take the first dose 7 or 14 days after your last Wegovy injection, as advised.
What to expect when you move to Mounjaro
- Food noise can fluctuate: Tirzepatide takes a few weeks to reach steady levels. Appetite may vary in the first fortnight even on an intermediate dose.
- Mild digestive change: Nausea, constipation, indigestion, or loose stools are common. Hydration, smaller meals, and less dietary fat help.
- Red flags: Severe abdominal pain radiating to the back, intractable vomiting, or signs of dehydration need urgent medical assessment to rule out pancreatitis. Stop treatment and seek help.
Switch safely with PrivateDoc
Changing incretin treatment should be a supervised decision. PrivateDoc maps your starting dose from current strength and side-effect history, sets a clear washout, and keeps messaging open through your patient portal.
If you are considering the other direction, see switching from Mounjaro to Wegovy. Oral options are covered in our Foundayo switch guide.
Disclaimer: This article is for general information only and does not replace personalised medical advice. Treatment is only authorised after a successful clinical assessment.
