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Compare Qsymia vs. Phentermine

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

Key takeaways

Phentermine/topiramate (Qsymia) and phentermine (Adipex-P) are both sympathomimetic medications used for weight loss. They help reduce appetite and are prescribed alongside a healthy diet and exercise. However, they differ in several ways. Qsymia is a combination of phentermine and topiramate, an antiepileptic, and is approved for long-term weight management in people aged 12 and older living with obesity or are living with overweight and have at least weight-related condition. In contrast, phentermine is approved for short-term use in adults aged 17 and older. Qsymia is taken once daily, while phentermine can be taken once or twice daily, depending on the form. Qsymia is not available as a generic, whereas phentermine comes in both a branded and lower-cost generic version. Common side effects of Qsymia include a "pins-and-needles" feeling, dry mouth, and constipation, while phentermine may cause dry mouth, trouble sleeping, and headache. Both medications are controlled substances, but Qsymia may increase the risk of birth defects and can only be filled at certified pharmacies.

  • Qsymia (phentermine / topiramate ER)
    Phentermine (Adipex-P)
  • Qsymia (phentermine / topiramate ER)
    Phentermine (Adipex-P)

  • Summary of Qsymia vs. Phentermine

    Summary for Sympathomimetic / Antiepileptic
    Prescription only

    Qsymia (phentermine / topiramate extended release) is a combination medication used to help with weight loss. It's approved for people over 12 who are considered obese and for some adults who are considered overweight. This medication is a tablet that you take once a day. You should also eat a balanced diet and exercise regularly for best results. Side effects include a "pins-and-needles" feeling, dry mouth, and constipation. You can only get this medication through the Qsymia REMS (Risk Evaluation and Mitigation Strategies) program because of the risk of birth defects if taken during pregnancy.

    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 Qsymia vs. Phentermine

    Indications for
    •Weight loss and long-term weight management, together with diet and exercise, for certain people:
    •People age 12 years and older considered obese
    •Adults considered overweight with at least one weight-related condition (e.g., heart disease, high blood pressure, Type 2 diabetes)
    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 Qsymia vs. Phentermine

    Pros and Const for Sympathomimetic / Antiepileptic
    Pros
    •A pill that's taken once a day
    •Combines two ingredients that help lower appetite into one pill for convenience
    •An option for certain children 12 years and older, if diet and exercise aren't enough
    Cons
    •Can raise the risk of depression or thoughts of self-harm
    •Controlled substance and only available through a REMS program
    •Not safe during pregnancy
    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 Qsymia vs. Phentermine

    Common Side Effects for

    Adults:

    •Feeling of pins and needles (up to 20%)
    •Dry mouth (up to 19%)
    •Constipation (up to 16%)
    •Upper respiratory tract infection (up to 16%)
    •Headache (up to 11%)
    •Change in taste (up to 9%)
    •Trouble sleeping (up to 9%)
    •Dizziness (up to 9%)

    Children:

    •Depression (up to 4%)
    •Nausea (up to 4%)
    •Fever (up to 4%)
    •Dizziness (up to 4%)
    •Joint pain (up to 4%)
    Common Side Effects for
    •Dry mouth
    •Headache
    •Tremor
    •Constipation
    •Diarrhea
    •High blood pressure
    •Fast heart rate
    •Difficulty sleeping

  • Warnings of Qsymia vs. Phentermine

    Common Side Effects for
    •Harm to an unborn baby
    •Mood problems and suicidal thoughts or behavior
    •Fast heart beat
    •Vision problems
    •Problems concentrating
    •Higher level of acid in blood (metabolic acidosis)
    •Possible lower kidney function
    •Kidney stones
    •High body temperature and inability to sweat
    •Serious allergic reactions and skin reactions
    •Possible slowed growth in children
    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 Qsymia vs. Phentermine

    Learn more about Qsymia
    Learn more about Phentermine

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