Tirzepatide in South Africa: Mounjaro & the Dual Agonist Explained

Tirzepatide is the active ingredient in Mounjaro. It's a “dual agonist” — it activates two gut-hormone receptors (GIP and GLP-1) rather than one, which is why it produced the largest average weight loss of any medicine in head-to-head trials.

What tirzepatide is

Tirzepatide is made by Eli Lilly and sold as Mounjaro. Like semaglutide it's a once-weekly injection that reduces appetite and slows gastric emptying — but it adds a second mechanism.

Why tirzepatide is different

Most weight-loss injections target one receptor (GLP-1). Tirzepatide targets two: GLP-1 and GIP (glucose-dependent insulinotropic polypeptide). Engaging both appears to enhance appetite suppression and metabolic effects, which is the leading explanation for its larger average weight loss. Compare the molecules in semaglutide vs tirzepatide.

How well tirzepatide works

In SURMOUNT-1, tirzepatide produced up to about 21–22.5% average weight loss at the top dose over 72 weeks. In the head-to-head SURMOUNT-5 trial it outperformed semaglutide (~20.2% vs 13.7%). These are averages alongside lifestyle changes; individual results vary.

Side effects

Side effects are similar to the GLP-1 drugs — mainly gastrointestinal and dose-related — with the same rare-but-serious cautions. See our side effects guide.

Tirzepatide price in SA

As Mounjaro, roughly R3 500–R4 600 a month at maintenance. See the price guide.

Frequently asked questions

Is tirzepatide the same as Mounjaro?

Tirzepatide is the active ingredient; Mounjaro is the brand sold in SA.

Is tirzepatide better than semaglutide?

On average weight loss, tirzepatide outperformed semaglutide in a head-to-head trial. “Better” also depends on price, tolerance and availability. See the comparison.

Sources & references

We cite primary sources and paraphrase them. Last reviewed June 2026. See our editorial policy and full sources hub.

1SAHPRA — registered health products & safety alerts — South African Health Products Regulatory Authority. SA registration status of medicines and counterfeit / falsified-product warnings.

2SURMOUNT-1 — tirzepatide for weight management — New England Journal of Medicine (Jastreboff et al., 2022). Average weight loss with tirzepatide (up to ~21–22.5% at highest dose).

3SURMOUNT-5 — tirzepatide vs semaglutide head-to-head — New England Journal of Medicine (Aronne et al., 2025). Direct comparison favouring tirzepatide (~20.2% vs 13.7% weight loss).

4SA Medicine Price Registry (SEP database) — National Department of Health. Single Exit Price reference for medicines sold in SA.

5Manufacturer Patient Information Leaflets (Novo Nordisk / Eli Lilly) — Novo Nordisk; Eli Lilly. Approved dosing, administration and side-effect information.

Tirzepatide