FAQ · GLP-1
GLP-1 FAQ
UK answers to the questions most readers ask about Mounjaro, Wegovy, and GLP-1 medications generally.
What is the difference between Mounjaro and Wegovy?
Mounjaro is tirzepatide (dual GIP + GLP-1 agonist). Wegovy is semaglutide (GLP-1 only). Mounjaro produces more weight loss on trial data (~22% vs ~15% at maximum dose). Wegovy now has a cardiovascular outcome indication.
How do I get Mounjaro on the NHS?
NHS Cohort 1 (BMI 40+, 4+ comorbidities) has been live since June 2025. Cohort 2 launches 23 June 2026 (BMI 35+, 3+ comorbidities). Cohort 3 expected April 2027 (BMI 30+, 2+ comorbidities). Ethnicity-adjusted thresholds are 2.5 kg/m² lower.
How much does Mounjaro cost privately in the UK?
Online pharmacies start around £150 to £200 per month at maintenance dose. High-touch private clinics cost £200 to £300 per month including coaching and app support. Lilly raised UK Mounjaro list prices up to 170% in September 2025.
I missed a dose of Mounjaro, what should I do?
Mounjaro 4-day rule: if you remember within 4 days, take it. If beyond 4 days, skip and take the next dose on the usual day. Wegovy uses a 5-day rule. Never double up to make up for a missed dose.
What are the side effects of Mounjaro?
Most common: nausea, diarrhoea, constipation, fatigue, reduced appetite (the latter is the medication working). Most settle in 2 to 4 weeks. The MHRA added pancreatitis to the patient information leaflet in 2025 as a rare but serious side effect. Severe constant abdominal pain is the red flag for A&E.
Will I regain the weight after stopping Mounjaro?
82% of people regain at least 25% of lost weight within 12 months of stopping (Oxford analysis, January 2026). Plan for aftercare before you start. Resistance training and protein at 1.4 to 1.8g/kg goal weight are the biggest behavioural levers.
Can I take Mounjaro during pregnancy?
No. Mounjaro and Wegovy are both contraindicated in pregnancy. UK guidance is to stop GLP-1 medication at least 2 months before trying to conceive. If you become pregnant unexpectedly, contact your prescriber the same day.
Can I switch from Wegovy to Mounjaro?
Yes. Most UK prescribers leave a 7-day gap between the last Wegovy dose and the first Mounjaro dose, restarting at Mounjaro 2.5 mg regardless of prior Wegovy dose. Speak with your prescriber.
Is Mounjaro better than Wegovy for me?
Mounjaro produces more weight loss on average. Wegovy now has a cardiovascular outcome indication and may be the right choice if you have established CV disease. Your prescriber decides what fits your file.
Does Mounjaro affect contraception?
Mounjaro may reduce the effectiveness of oral hormonal contraceptives because of delayed gastric emptying. The Lilly PIL recommends adding a barrier method or switching to a non-oral contraceptive when starting Mounjaro and for 4 weeks after each dose increase.
What happens to my face on Mounjaro?
Rapid weight loss reduces facial fat alongside body fat. The cosmetic effect is more pronounced after 35 because skin elasticity has declined. Slower pace of loss, resistance training, and protein help. Aesthetic clinic options exist if needed.
Is Mounjaro on the WADA list?
Yes. Both tirzepatide and semaglutide are on the WADA prohibited list (S2 peptide hormones). Tested athletes need a Therapeutic Use Exemption.