Contrave vs. Phentermine

See how Contrave and Phentermine compare on approved uses, dosing, side effects, and cost.

Key Takeaways

  • Contrave is FDA-approved for long-term chronic weight management, while phentermine is approved only for short-term use of a few weeks.

  • Contrave combines an opioid antagonist and an antidepressant to curb appetite and cravings, while phentermine is a stimulant-like amine that suppresses hunger directly.

  • Phentermine is a Schedule IV controlled substance with abuse and dependence risk, while Contrave carries a boxed warning for suicidal thoughts tied to its bupropion component.

Contrave vs. Phentermine Drug Summary

Contrave

Contrave combines naltrexone, an opioid antagonist, with bupropion, an antidepressant, to help reduce appetite and food cravings. It is FDA-approved for chronic weight management in adults with obesity, or who are overweight with a weight-related condition. The extended-release tablet is taken twice daily after a short dose-up schedule.

Phentermine

Phentermine is a stimulant-like appetite suppressant approved only for short-term weight loss, usually just a few weeks. It works by prompting the body to release norepinephrine, which reduces hunger signals. The tablet or capsule is taken once daily, typically in the morning.

Contrave vs. Phentermine Side Effects

Contrave

Most common
Nausea (up to 32.5%)
Constipation (up to 19.2%)
Headache (up to 17.6%)
Vomiting (up to 10.7%)

Phentermine

Most common
Palpitation (reported)
Tachycardia (reported)
Insomnia (reported)
Dry mouth (reported)

Contrave vs. Phentermine Dosage

Contrave

Dosage
Dosage Table
STAGE DOSE WHEN
Starting dose 8 mg/90 mg once daily Week 1
Maximum dose 16 mg/180 mg twice daily Week 3
Dose changes 2 increases Every week

Phentermine

Dosage
Dosage Table
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

Contrave vs. Phentermine Indications

Contrave

Contrave is FDA-approved for chronic weight management in adults with obesity, or who are overweight with at least one weight-related condition such as high blood pressure or type 2 diabetes. It is meant for long-term use alongside a reduced-calorie diet and increased physical activity. It is not approved for depression, smoking cessation, or use in children.

  • Chronic, long-term weight management

  • Adults with obesity (BMI ≥30) or overweight with a comorbidity

  • Used with reduced-calorie diet and exercise

  • Not approved for depression or smoking cessation

Phentermine

Phentermine is FDA-approved only as a short-term aid, typically just a few weeks, for weight reduction in adults with obesity. It is meant to be combined with exercise, behavior changes, and calorie restriction. It is not approved for long-term use or for patients 16 and younger.

  • Short-term use, typically a few weeks

  • Adults with BMI ≥30, or ≥27 with risk factors

  • Used with diet, exercise, and behavior change

  • Not approved for long-term weight management

Contrave vs. Phentermine Pros and Cons

Contrave

Contrave's combination of naltrexone and bupropion targets both appetite and food cravings, and it is approved for ongoing use rather than a few weeks. It is not a controlled substance, but it carries a boxed warning and several contraindications tied to its bupropion component.

Pros

  • Approved for long-term, ongoing weight management

  • Not a controlled substance, no abuse or dependence risk

  • May help reduce food cravings, not just appetite

  • Non-stimulant, less likely to cause jitteriness or rapid heartbeat

Cons

  • Boxed warning for suicidal thoughts and behaviors

  • Slower to reach full effective dose due to titration

  • Roughly $750 to $840 per month without insurance, pricier than phentermine

  • Contraindicated with seizure history, uncontrolled hypertension, or opioid use

Phentermine

Phentermine works quickly and costs far less than most prescription weight-loss options, but it is only meant for short-term use. As a controlled stimulant, it carries risks of dependence and cardiovascular side effects that Contrave does not share.

Pros

  • Roughly $15 to $75 per month without insurance, one of the least expensive weight-loss drugs

  • Fast-acting appetite suppression, no titration needed

  • Long track record of use since 1959

  • Simple once-daily dosing

Cons

  • Only approved for short-term use, a few weeks

  • Schedule IV controlled substance with abuse and dependence risk

  • Can raise heart rate and blood pressure

  • Withdrawal effects possible after prolonged high-dose use

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