Medication Comparison
GLP-1 Medications vs Phentermine
GLP-1 medications produce 2-4x more weight loss than phentermine with a completely different mechanism and safety profile. Phentermine is far cheaper ($10-30/mo vs $150-1,400/mo) but is limited to short-term use (12 weeks) and carries cardiovascular risks. GLP-1s represent a paradigm shift in obesity treatment.
| Category | GLP-1 Medications | Phentermine |
|---|---|---|
| Brands | Ozempic / Wegovy / Mounjaro / Zepbound | Adipex-P / Lomaira |
| Class | GLP-1 receptor agonists | Sympathomimetic amine (stimulant) |
| Administration | Weekly injection | Daily oral tablet |
| Average weight loss | ~15-22% | ~5-7% |
| Compounded cost | $150-450/mo (compounded) | $10-30/mo (generic) |
| Brand cost | $1,000-1,400/mo | $30-75/mo |
| Half-life | 5-7 days | ~20 hours |
| Dosing frequency | Once weekly | Once daily |
| Key trial | STEP and SURMOUNT programs | Various (5-7% weight loss over 12 weeks) |
Best for GLP-1 Medications
Patients seeking significant, sustained weight loss with metabolic benefits
Best for Phentermine
Patients needing short-term appetite suppression on a tight budget who have no cardiovascular risk
GLP-1 Medications tradeoffs
Pros
- Dramatically more weight loss
- Metabolic benefits beyond weight
- Long-acting with weekly dosing
Cons
- Expensive
- Injectable
- GI side effects common
Phentermine tradeoffs
Pros
- Very affordable
- Oral tablet
- Fast-acting appetite suppression
Cons
- Limited to 12-week use
- Stimulant side effects
- Weight regain after stopping
- Not for patients with heart conditions
Common questions
Are GLP-1s better than phentermine?
For sustained weight loss, yes. GLP-1s produce significantly more weight loss (15-22% vs 5-7%), can be used long-term, and have metabolic benefits. Phentermine is limited to 12 weeks and carries stimulant risks.
Can I take phentermine and a GLP-1 together?
Some doctors prescribe them together, especially during the GLP-1 titration period. However, this is off-label and should only be done under medical supervision.
Why would anyone choose phentermine over GLP-1s?
Cost is the main reason — phentermine is $10-30/mo vs $150-1,400/mo for GLP-1s. It also works immediately and is a simple pill. Some patients use it as a bridge while waiting for GLP-1 access.
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