Compare Orlistat vs. Mounjaro
Orlistat is the most accessible weight loss medication in Australia, available over-the-counter at $50-80/month with ~3-5% weight loss. Mounjaro is the most effective, producing ~21% weight loss as a weekly injection at $395+/month. They work by completely different mechanisms: Orlistat blocks fat absorption in the gut while Mounjaro targets GIP and GLP-1 receptors.
Compare Orlistat vs Mounjaro at a Glance
Compare Orlistat vs Mounjaro Cost in Australia
Private prescription cost per month in AUD.
Compare Orlistat vs Mounjaro Weight Loss Efficacy
Orlistat Clinical Trials
XENDOS
5.8kg loss vs 3kg placebo
Multiple Phase 3
~3-5% body weight reduction
Mounjaro Clinical Trials
SURMOUNT-1
20.9% weight loss (15mg)
SURMOUNT-2
15.7% weight loss (diabetes pop.)
SURMOUNT-3
25.3% weight loss (with lifestyle intervention)
SURMOUNT-OSA
Significant improvement in sleep apnoea
Clinical trial data at highest approved doses. Individual results vary.
Compare Orlistat vs Mounjaro Side Effects
Orlistat
Very common
- Oily/fatty stools
- Oily spotting
- Increased flatulence
- Faecal urgency
Common
- Abdominal discomfort
- Liquid stools
- Frequent bowel movements
- Headache
Serious (rare)
- Liver injury (very rare)
- Kidney stones (rare)
- Reduced fat-soluble vitamin absorption (A,D,E,K)
- May affect absorption of some medications
Mounjaro
Very common
- Nausea (up to 33%)
- Diarrhoea (up to 23%)
- Decreased appetite
Common
- Vomiting
- Constipation
- Abdominal pain
- Dyspepsia
- Injection site reactions
Serious (rare)
- Pancreatitis
- Hypoglycaemia (with insulin)
- Gallbladder disease
- Thyroid tumour risk (animal data)
- May reduce effectiveness of oral contraceptives
Compare How Orlistat and Mounjaro Work
Orlistat
Lipase inhibitor
Completely different mechanism to GLP-1 drugs. Inhibits gastric and pancreatic lipase enzymes, preventing approximately 30% of dietary fat from being absorbed. Unabsorbed fat passes through the digestive system. Does not affect appetite or the brain. Most effective with a reduced-fat diet.
Mounjaro
Dual GIP/GLP-1 receptor agonist
First dual-agonist: targets both GIP and GLP-1 receptors simultaneously. This dual mechanism produces greater weight loss than GLP-1-only drugs. Reduces appetite, slows gastric emptying, improves insulin sensitivity, with additional metabolic benefits through the GIP pathway.
Compare Orlistat vs Mounjaro Dosing Schedule
Orlistat
Oral capsule with meals (up to 3x daily)
| Dose | Period | Note |
|---|---|---|
| 60mg OTC | With each meal | Up to 3 capsules/day |
| 120mg Rx | With each meal | Up to 3 capsules/day |
Mounjaro
Weekly injection
| Dose | Period | Note |
|---|---|---|
| 2.5mg | Weeks 1-4 | Starting dose |
| 5mg | Weeks 5-8 | Escalation / maintenance |
| 7.5mg | Weeks 9-12 | Escalation |
| 10mg | Weeks 13-16 | Escalation / maintenance |
| 12.5mg | Weeks 17-20 | Escalation |
| 15mg | Week 21+ | Maximum maintenance |
Compare Orlistat vs Mounjaro Australian Regulatory Status
Orlistat
- TGA Status
- Registered (OTC and prescription strengths)
- PBS Listed
- No PBS listing
- OTC Availability
- 60mg available without prescription at pharmacies
- Key Advantage
- No needles, no Rx for lower dose, cheapest option, longest safety record
- Limitation
- Modest weight loss vs GLP-1 drugs; GI side effects related to fat intake
Mounjaro
- TGA Status
- Registered on ARTG for T2D, weight management, and OSA
- PBS Listed
- No PBS listing for any indication
- Zepbound Brand
- US/UK weight loss brand name not used in Australia
- Supply Status
- Availability improving; no critical shortage reported
- Oral Version
- Eli Lilly's oral GLP-1 (orforglipron) expected FDA decision mid-2026; not yet in AU
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We are not medical professionals and nothing on this page constitutes medical advice, diagnosis, or treatment. Always consult a qualified doctor or specialist before making any decisions about medication.
The weight loss medication landscape in Australia is changing rapidly. Information on this page may become outdated without notice. Data sourced from the TGA, FDA, MHRA, NICE, PBAC, Australian Prescriber, Obesity Evidence Hub, and clinical trial publications. Last reviewed March 2026.