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Compare Contrave vs. Phentermine

Head-to-head comparisons of medication uses, side effects, warnings, and more.

Key takeaways

Contrave (naltrexone / bupropion) and Adipex-P (phentermine) are both medications used to help with weight loss in adults with a high body mass index (BMI) and weight-related conditions. However, they belong to different medication classes and have distinct mechanisms of action. Contrave combines an opioid antagonist (naltrexone) and a dopamine and norepinephrine reuptake inhibitor (bupropion) to help control appetite and cravings. In contrast, Adipex-P is a sympathomimetic stimulant that suppresses appetite. Contrave is taken as a tablet twice daily after taking it once daily for a week or more, while Adipex-P is typically taken once daily in the morning. Contrave is not available as a generic, whereas Adipex-P is available as a lower-cost generic. Common side effects of Contrave include nausea and headache, and rare but serious risks include seizures and mood changes. Adipex-P can cause dry mouth and trouble sleeping, with risks of high blood pressure and dependence. Contrave should not be taken with opioids due to the possibility of withdrawal. Adipex-P is a controlled substance due to its potential for misuse.

  • Contrave (naltrexone / bupropion)
    Phentermine (Adipex-P)
  • Contrave (naltrexone / bupropion)
    Phentermine (Adipex-P)

  • Summary of Contrave vs. Phentermine

    Summary for Opioid antagonist / Dopamine and norepinephrine reuptake inhibitor
    Prescription only

    Contrave is a combination medication that helps with weight loss for certain adults. It's taken along with a balanced diet and exercise plan. Contrave is a tablet with two active ingredients that help regulate your appetite. They are naltrexone (an opioid antagonist) and bupropion (a dopamine and norepinephrine reuptake inhibitor). Your dosage will slowly increase over the first 3 weeks. Then, you take the maintenance dose of two tablets by mouth twice a day. Some side effects are nausea, constipation, and headache. But it can also have serious risks, like unusual changes in behavior. Contrave is brand name only; there isn't a generic version available yet.

    Summary for Sympathomimetic
    Prescription only

    Phentermine (Adipex-P) is an appetite suppressant. It's a prescription weight loss pill for people ages 17 years and older. This medication works best when it's part of a treatment plan that involves healthy diet and regular exercise. Phentermine (Adipex-P) is taken by mouth once daily, typically in the morning. Some of the more common side effects of this medication include dry mouth, trouble sleeping, and headache.

  • Indications of Contrave vs. Phentermine

    Indications for
    •Long-term weight management in certain adults
    •Adults with a body mass index (BMI) of 30 kg/m2 or greater
    •Adults with a BMI of 27 kg/m2 or greater and a weight-related condition (e.g., high blood pressure, Type 2 diabetes, high cholesterol)
    Indications for

    Short-term treatment for weight management in adults with a body mass index (BMI) of:

    •30 kg/m2 or greater; or
    •27 kg/m2 or greater, and with at least one other weight-related condition (e.g., high blood pressure, high blood sugar, high cholesterol)

  • Pros and Cons of Contrave vs. Phentermine

    Pros and Const for Opioid antagonist / Dopamine and norepinephrine reuptake inhibitor
    Pros
    •Comes as a tablet that you take by mouth
    •Might start to notice results in as early as 4 weeks (when taken along with a balanced diet and regular exercise)
    Cons
    •Must take twice a day (after the dose ramp-up at the beginning)
    •Might raise your risk of unusual behavior and thoughts of self-harm
    •Interacts with a lot of medications
    Pros and Const for Sympathomimetic
    Pros
    •Can help you lose 5% to 10% of body weight
    •Usually taken by mouth once per day
    •Available as a lower-cost generic
    •Comes as tablets, capsules, and orally disintegrating tablets
    Cons
    •Most insurance companies don't cover the cost of phentermine (Adipex-P).
    •Has a risk of misuse and dependence since it's a stimulant medication that's similar to amphetamines
    •Might not be a good choice for people with high blood pressure
    •Should be avoided in children 16 years of age and younger, pregnant and breastfeeding women, and people with serious heart problems

  • Common Side Effects of Contrave vs. Phentermine

    Common Side Effects for
    •Nausea (33%)
    •Constipation (19%)
    •Headache (18%)
    •Vomiting (11%)
    •Dizziness (10%)
    •Trouble sleeping (9%)
    •Dry mouth (8%)
    •Diarrhea (7%)
    Common Side Effects for
    •Dry mouth
    •Headache
    •Tremor
    •Constipation
    •Diarrhea
    •High blood pressure
    •Fast heart rate
    •Difficulty sleeping

  • Warnings of Contrave vs. Phentermine

    Common Side Effects for
    •Risk of suicidal thoughts and behavior
    •Possible changes in thoughts, behavior, and mood
    •Seizures
    •Don't take Contrave with opioid medications
    •Higher blood pressure and faster heart rate
    •Liver problems
    •Mania (extreme enthusiasm or excitement)
    •Worsening of glaucoma in certain people
    •Potential risk of low blood sugar in people taking certain medications for Type 2 diabetes
    Common Side Effects for
    •Not safe to combined with other weight loss medications
    •Phentermine not working well
    •Risk of misuse and dependence
    •Trouble concentrating or problem with coordination
    •Heart and lung problems
    •Risk of high blood pressure
    •Risk of low blood sugar in people with diabetes

  • Prices with our coupons for Contrave vs. Phentermine

    Learn more about Contrave
    Learn more about Phentermine

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