Saxenda vs. Phentermine
See how Saxenda and Phentermine compare on approved uses, dosing, side effects, and cost.
Key Takeaways
Saxenda is a daily GLP-1 injection approved for long-term weight management, while phentermine is an oral stimulant approved only for short-term use of a few weeks.
Saxenda carries a boxed warning for thyroid tumors and common GI side effects, while phentermine's main risks are cardiovascular stimulation and dependence as a controlled substance.
Phentermine costs far less per month than Saxenda, but only Saxenda has FDA backing for sustained weight loss over time.
Saxenda vs. Phentermine Drug Summary
Saxenda
Saxenda (liraglutide) is a GLP-1 receptor agonist for chronic weight management in adults with obesity, or overweight with a weight-related condition, and in adolescents 12 to 17 with obesity. It's injected once daily, starting low and increasing weekly to a 3 mg maintenance dose.
Phentermine
Phentermine is a sympathomimetic amine, chemically similar to amphetamine, that suppresses appetite and boosts energy. It's taken as a once-daily oral tablet, but is FDA-approved only for short-term use, typically just a few weeks, alongside diet and exercise changes.
Saxenda vs. Phentermine Side Effects
Saxenda
Phentermine
Saxenda vs. Phentermine Dosage
Saxenda
Phentermine
| STAGE | DOSE | WHEN |
| Starting dose | 0.6 mg once daily | Week 1 |
| Maximum dose | 3 mg once daily | Week 5 onward |
| Dose changes | 4 increases | Every week |
| STAGE | DOSE | WHEN |
| Starting dose | 37.5 mg once daily | At the start |
| Maximum dose | 15 mg once daily | If needed |
| Dose changes | 1 increase | As tolerated |
Saxenda
| STAGE | DOSE | WHEN |
| Starting dose | 0.6 mg once daily | Week 1 |
| Maximum dose | 3 mg once daily | Week 5 onward |
| Dose changes | 4 increases | Every week |
Phentermine
| STAGE | DOSE | WHEN |
| Starting dose | 37.5 mg once daily | At the start |
| Maximum dose | 15 mg once daily | If needed |
| Dose changes | 1 increase | As tolerated |
Saxenda vs. Phentermine Indications
Saxenda
Saxenda is FDA-approved for chronic weight management, meaning it's meant for long-term use rather than a short course. It works by mimicking a gut hormone that reduces appetite and slows digestion, and it's the only weight-loss GLP-1 approved for teens 12 to 17.
Chronic weight management in adults with obesity
Adults who are overweight with a weight-related condition
Adolescents 12-17 with obesity
Not approved for diabetes control (that's Victoza)
Phentermine
Phentermine is FDA-approved only as a short-term adjunct, typically just a few weeks, for weight reduction alongside diet, exercise, and behavior changes. It's intended for patients with a BMI of 30 or higher, or 27 or higher with an additional risk factor like high blood pressure.
Short-term (a few weeks) adjunct for weight loss
BMI of 30+, or 27+ with a risk factor
Used with diet, exercise, behavior changes
Not approved for long-term use or under age 16
Saxenda vs. Phentermine Pros and Cons
Saxenda
Saxenda has a long track record as the first GLP-1 approved specifically for weight loss, with outcomes data across adults and teens. It requires a daily injection and carries a boxed warning for thyroid C-cell tumors, and gastrointestinal side effects are common during dose escalation.
Pros
FDA-approved for long-term chronic weight management
Also approved for adolescents 12 to 17 with obesity
GLP-1 mechanism gives more substantial average weight loss
Once-daily dosing schedule is predictable and steady
Cons
Requires a daily self-injection, unlike a pill
Boxed warning for thyroid C-cell tumors
Common GI side effects like nausea and vomiting
Typically costs $1,300 to $1,350 per month without insurance
Phentermine
Phentermine has decades of clinical use and works quickly to curb appetite, but the FDA only approved it for short courses of a few weeks. As a Schedule IV controlled substance with stimulant effects, it carries risks of dependence and cardiovascular side effects like increased heart rate.
Pros
Oral tablet or capsule, no injections needed
Long history of use dating back to 1959
Typically costs $15 to $75 per month without insurance
Fast-acting appetite suppression
Cons
Only approved for short-term use of a few weeks
Schedule IV controlled substance with abuse potential
Can raise heart rate and blood pressure
Not approved for patients 16 and younger
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