Is long-term use safe?
The longest published safety data for GLP-1 weight loss medications:
- Semaglutide (Wegovy): 4-year data from the SELECT trial (17,604 participants). No new safety signals. Actually showed cardiovascular benefit (20% MACE reduction).
- Tirzepatide (Mounjaro): 2-year data available. Safety profile consistent with shorter trials.
- Phentermine (Duromine): NOT for long-term use (12 weeks maximum).
- Orlistat (Xenical): Longest track record — used safely for decades.
While 4 years of data is reassuring, longer-term effects beyond this period are not yet known. Your doctor should monitor you regularly with follow-up appointments and periodic blood tests.
The cost of long-term treatment
| Medication | Annual cost | 5-year cost | 10-year cost |
|---|---|---|---|
| Wegovy | ~$5,000 | ~$25,000 | ~$50,000 |
| Mounjaro | ~$5,500 | ~$27,500 | ~$55,000 |
| Contrave | ~$3,600 | ~$18,000 | ~$36,000 |
| Xenical | ~$1,000 | ~$5,000 | ~$10,000 |
If Wegovy gets PBS listed, the cost drops to ~$380/year for eligible patients — transforming the long-term economics.
Ongoing monitoring
Long-term medication requires regular medical oversight:
- Follow-up consultations every 1–3 months
- Blood tests: blood sugar, kidney function, liver function, lipids (every 6–12 months)
- Blood pressure and heart rate monitoring
- Assessment of continued benefit vs any emerging side effects
- Nutritional assessment — especially protein intake and fat-soluble vitamins
Can you reduce the dose over time?
Some patients successfully maintain weight loss at a lower dose than the maximum. This can reduce costs and side effects. Discuss dose optimisation with your doctor once your weight has stabilised — but don't reduce unilaterally.
What happens if you stop?
Research consistently shows significant weight regain after stopping GLP-1 medications — approximately two-thirds of lost weight within 1–2 years. This is biology, not failure. The medication counteracts hormonal weight-defence mechanisms that resume when treatment stops.