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Qsymia Side Effects

Generic Name: phentermine / topiramate

Note: This page contains side effects data for the generic drug phentermine / topiramate. It is possible that some of the dosage forms included below may not apply to the brand name Qsymia.

It is possible that some side effects of Qsymia may not have been reported. These can be reported to the FDA here. Always consult a healthcare professional for medical advice.

For the Consumer

Applies to phentermine / topiramate: oral capsule extended release

As well as its needed effects, phentermine / topiramate may cause unwanted side effects that require medical attention.

If any of the following side effects occur while taking phentermine / topiramate, check with your doctor immediately:

Less common
  • Chest discomfort
  • convulsions
  • decreased urine
  • fast, irregular, pounding, or racing heartbeat or pulse
  • loss of appetite
  • mood changes
  • muscle pain or cramps
  • nausea or vomiting
  • numbness or tingling in the hands, feet, or lips
  • shortness of breath
  • unusual tiredness or weakness
  • Blood in the urine
  • pain in the groin or genitals
  • sharp back pain just below the ribs
Incidence not known
  • Blistering, peeling, or loosening of the skin
  • blisters on the mouth, trunk, scalp, or other areas
  • blurred or decreased vision
  • chest pain
  • chills or shivering
  • clumsiness
  • continuing nausea or vomiting
  • cough or sore throat
  • dark urine
  • diarrhea or light-colored stools
  • dizziness
  • headache
  • increase in the frequency of seizures
  • irregular heartbeat
  • itching
  • joint or muscle pain
  • loss of appetite
  • low body temperature
  • muscle aches or weakness
  • pain in the shoulders, arms, jaw, or neck
  • red skin lesions, often with a purple center
  • red, irritated eyes
  • shakiness in the legs, arms, hands, or feet
  • sores, ulcers, or white spots in the mouth or on the lips
  • sweating
  • swelling of the face
  • tiredness and weakness
  • trouble thinking, speaking, or walking
  • upper right abdominal or stomach pain
  • weak or feeble pulse
  • weight gain
  • yellow eyes or skin

Some phentermine / topiramate side effects may not need any medical attention. As your body gets used to the medicine these side effects may disappear. Your health care professional may be able to help you prevent or reduce these side effects, but do check with them if any of the following side effects continue, or if you are concerned about them:

More common
  • Back pain
  • change in taste
  • difficulty having a bowel movement (stool)
  • ear congestion
  • fear or nervousness
  • loss of taste
  • loss of voice
  • memory problems
  • pain or tenderness around the eyes and cheekbones
  • sneezing
  • stuffy or runny nose
  • trouble sleeping
Less common
  • Belching
  • cramps
  • decreased appetite
  • dry eyes
  • eye pain
  • hair loss
  • heartburn or indigestion
  • heavy bleeding
  • irritability
  • rash
  • stomach discomfort, upset, or pain
Incidence not known
  • Bloating
  • false or unusual sense of well-being
  • feeling that others are watching you or controlling your behavior
  • feeling that others can hear your thoughts
  • feeling, seeing, or hearing things that are not there
  • hives or welts
  • change in sexual ability, desire, drive, or performance
  • severe mood or mental changes
  • unusual behavior

For Healthcare Professionals

Applies to phentermine / topiramate: oral capsule extended release

Nervous system

Very common (10% or more): Paraesthesia (up to 19.9%), headache (up to 10.6%)
Common (1% to 10%): Dysgeusia, dizziness, hypoesthesia, disturbance in attention, cognitive impairment

Postmarketing reports: Euphoria, psychosis, tremor[Ref]


Common (1% to 10%): Insomnia, anxiety, depression/mood problems, irritability
Postmarketing reports: Suicidal ideation, suicidal behavior

Postmarketing reports: Libido changes, impotence[Ref]


Very common (10% or more): Decreased serum bicarbonate (up to 12.8%)
Common (1% to 10%): Hypokalemia, decreased serum potassium, decreased appetite

Postmarketing reports: Hyperammonemia[Ref]


Common (1% to 10%): Elevated serum creatinine, nephrolithiasis[Ref]


Very common (10% or more): Elevated resting heart rate (up to 77.7%)
Common (1% to 10%): Palpitations

Postmarketing reports: Elevated blood pressure, ischemic events[Ref]


Common (1% to 10%): Blurred vision, dry eye, eye pain
Postmarketing reports: Acute angle closure glaucoma, increased intraocular pressure

Postmarketing reports: Maculopathy[Ref]


Common (1% to 10%): Fatigue, thirst, chest discomfort, procedural pain

Postmarketing reports: Hypothermia[Ref]


Common adverse reactions occurring at a rate of 5% or more and at a rate of at least 1.5 times placebo include paraesthesia, dizziness, dysgeusia, insomnia, constipation, and dry mouth.[Ref]


Common (1% to 10%): Alopecia, rash

Postmarketing reports: Bullous skin reactions (including erythema multiforme, Stevens-Johnson syndrome, toxic epidermal necrolysis), pemphigus[Ref]


Very common (10% or more): Dry mouth (up to 19.1%), constipation (up to 16.1%)
Common (1% to 10%): Nausea, diarrhea, gastroesophageal reflux disease, dyspepsia, oral paraesthesia, gastroenteritis

Postmarketing reports: Pancreatitis[Ref]


Common (1% to 10%): Dysmenorrhea, urinary tract infection[Ref]


Postmarketing reports: Hepatic failure (including fatalities), hepatitis[Ref]


Postmarketing reports: Urticaria[Ref]


Common (1% to 10%): Influenza[Ref]


Common (1% to 10%): Back pain, extremity pain, muscle spasms, musculoskeletal pain, neck pain[Ref]


Very common (10% or more): Upper respiratory tract infection (up to 15.8%), nasopharyngitis (up to 12.5%)
Common (1% to 10%): Sinusitis, bronchitis, cough, sinus congestion, pharyngolaryngeal pain, nasal congestion[Ref]


1. "Product Information. Qsymia (phentermine-topiramate)." Vivus Inc, Mountain View, CA.

Disclaimer: Every effort has been made to ensure that the information provided is accurate, up-to-date and complete, but no guarantee is made to that effect. In addition, the drug information contained herein may be time sensitive and should not be utilized as a reference resource beyond the date hereof. This material does not endorse drugs, diagnose patients, or recommend therapy. This information is a reference resource designed as supplement to, and not a substitute for, the expertise, skill , knowledge, and judgement of healthcare practitioners in patient care. The absence of a warning for a given drug or combination thereof in no way should be construed to indicate safety, effectiveness, or appropriateness for any given patient. does not assume any responsibility for any aspect of healthcare administered with the aid of materials provided. The information contained herein is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. If you have questions about the substances you are taking, check with your doctor, nurse, or pharmacist.