Qsymia vs. Adipex

See how Qsymia and Adipex compare on approved uses, dosing, side effects, and cost.

Key Takeaways

  • Qsymia combines phentermine and topiramate for long-term chronic weight management, while Adipex is phentermine alone approved only for short-term use of a few weeks.

  • Both are Schedule IV controlled substances with overlapping stimulant side effects like insomnia and dry mouth, but Qsymia requires REMS enrollment due to a birth-defect risk.

  • Qsymia typically costs more per month than Adipex, which reflects its combination formulation and its approval for ongoing, rather than short-term, use.

Qsymia vs. Adipex Drug Summary

Qsymia

Qsymia combines phentermine, a stimulant appetite suppressant, with topiramate, an anticonvulsant, in one once-daily capsule. It is FDA-approved for chronic weight management in adults with obesity or overweight plus a weight-related condition, and in adolescents 12 and older. The dose is increased gradually over several months to balance weight loss against side effects.

Adipex

Adipex is phentermine alone, a stimulant that suppresses appetite, taken as a once-daily or twice-daily tablet or capsule. It is FDA-approved only for short-term use, typically just a few weeks, alongside diet and exercise for weight loss in adults with obesity. Unlike Qsymia, it is not approved for long-term chronic weight management.

Qsymia vs. Adipex Side Effects

Qsymia

Most common
dry mouth (up to 19%)
insomnia (up to 11%)
paresthesia (up to 21%)
constipation (up to 16%)

Adipex

Most common
dry mouth (not specified)
insomnia (not specified)
dizziness (not specified)
restlessness (not specified)

Qsymia vs. Adipex Dosage

Qsymia

Dosage
Dosage Table
STAGE DOSE WHEN
Starting dose 3.75 mg/23 mg once daily Days 1-14
Maximum dose 15 mg/92 mg once daily Week 17 onward
Dose changes 3 increases As tolerated

Adipex

Dosage
Dosage Table
STAGE DOSE WHEN
Starting dose 18.75 mg once daily At the start
Maximum dose 15 mg once daily If needed
Dose changes 3 increases As tolerated

Qsymia vs. Adipex Indications

Qsymia

Qsymia is FDA-approved as a long-term treatment for chronic weight management, not just a short-term jumpstart. It can be used in adults with obesity, adults who are overweight with a related condition like high blood pressure, and in adolescents 12 and older with obesity.

  • Chronic weight management in adults with obesity

  • Adults who are overweight with a weight-related condition

  • Adolescents 12 years and older with obesity

  • Requires REMS certified-pharmacy dispensing

Adipex

Adipex is FDA-approved only as a short-term adjunct to diet and exercise, meant to be used for just a few weeks. It is approved for adults with obesity but not for adolescents 16 or younger, and it is not intended for ongoing, long-term treatment.

  • Short-term weight-loss adjunct to diet and exercise

  • Approved only for adults with obesity

  • Not approved for long-term chronic use

  • Not approved for patients 16 years or younger

Qsymia vs. Adipex Pros and Cons

Qsymia

Qsymia pairs phentermine with topiramate, producing greater weight loss than phentermine alone in trials, and it is approved for long-term use. Because topiramate carries a birth-defect risk, it requires REMS enrollment, monthly pregnancy testing, and certified-pharmacy dispensing.

Pros

  • FDA-approved for long-term chronic weight management

  • Approved for adolescents 12 and older

  • Combination mechanism may produce greater weight loss than phentermine alone

  • Once-daily dosing with a structured titration schedule

Cons

  • Requires REMS enrollment and certified-pharmacy dispensing

  • Monthly pregnancy testing required due to birth-defect risk

  • Contraindicated in glaucoma and hyperthyroidism

  • Roughly $200 to $350 per month without insurance, before savings programs

Adipex

Adipex has decades of use as a stand-alone appetite suppressant and typically costs far less than Qsymia. It is approved only for short-term treatment of a few weeks, so it is not designed for the type of ongoing management that chronic obesity often requires.

Pros

  • Roughly $50 to $150 per month without insurance, before savings programs

  • Simple once- or twice-daily dosing without REMS requirements

  • Long clinical track record dating back to 1959

  • Available generically in several dose strengths

Cons

  • Approved only for short-term use of a few weeks

  • Contraindicated with a history of cardiovascular disease

  • Rare risk of pulmonary hypertension and heart valve problems

  • Not approved for chronic, long-term weight management

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