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- Clinician Information:
Qsymia Side Effects Center
Medical Editor: John P. Cunha, DO, FACOEP
Qsymia (phentermine and topiramate extended-release) is indicated as an adjunct to a reduced-calorie diet and increased physical activity for chronic weight management in overweight and obese adults. Phentermine is an appetite suppressant and stimulant, and topiramate is a seizure medication. Side effects of Qsymia can include mood changes such as depression and trouble sleeping. Other side effects can include confusion, problems with concentration, attention, memory or speech.
Dosing of Qsymia is based on the body mass index (BMI) of the patient. Start treatment with Qsymia 3.75 mg/23 mg (phentermine 3.75 mg/topiramate 23 mg extended-release) daily for 14 days; after 14 days increase to the recommended dose of Qsymia 7.5 mg/46 mg (phentermine 7.5 mg/topiramate 46 mg extended-release) once daily. Weight loss should be evaluated 12 weeks after the start of treatment. Other medications may interact with Qsymia. Tell your doctor all medications you use. If this drug is used during pregnancy, or if a patient becomes pregnant while taking this drug, treatment should be discontinued immediately and the patient should be apprised of the potential hazard to a fetus. It is not known if Qsymia passes into breast milk. Consult your doctor before breastfeeding. Withdrawal symptoms may occur if you suddenly stop taking this medication.
Our Qsymia Side Effects Drug Center provides a comprehensive view of available drug information on the potential side effects when taking this medication.
This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.
What is Prescribing information?
The FDA package insert formatted in easy-to-find categories for health professionals and clinicians.
Qsymia FDA Prescribing Information: Side Effects
The following important adverse reactions are described below and elsewhere in the labeling:
- Fetal Toxicity: [see WARNINGS AND PRECAUTIONS and Use in Specific Populations]
- Elevation in Heart Rate [see WARNINGS AND PRECAUTIONS]
- Suicidal Behavior and Ideation [see WARNINGS AND PRECAUTIONS]
- Acute Angle Closure Glaucoma [see WARNINGS AND PRECAUTIONS]
- Mood and Sleep Disorders [see WARNINGS AND PRECAUTIONS]
- Cognitive Impairment [see WARNINGS AND PRECAUTIONS]
- Metabolic Acidosis [see WARNINGS AND PRECAUTIONS]
Clinical Trials Experience
Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical studies of another drug and may not reflect the rates observed in practice.
The data described herein reflects exposure to Qsymia in two, 1-year, randomized, double-blind, placebocontrolled, multicenter clinical trials, and two Phase 2 supportive trials in 2318 adult patients (936 [40.4%] patients with hypertension, 309 [13.3%] patients with type 2 diabetes, 808 [34.9%] patients with BMI greater than 40 kg/m²) exposed for a mean duration of 298 days.
Common Adverse Reactions
Adverse reactions reported in greater than or equal to 2% of Qsymia-treated patients and more frequently than in the placebo group are shown in Table 3.
Table 3: Adverse Reactions Reported in Greater Than or Equal to 2% of Patients and More Frequently with than Placebo during 1 Year of Treatment - Overall Study Population
|System Organ Class Preferred Term||Placebo
(N = 1561) %
|Qsymia 3.75 mg/23 mg
(N = 240) %
|Qsymia 7.5 mg/46 mg
(N = 498) %
|Qsymia 15 mg/92 mg
(N = 1580) %
|Nervous System Disorders|
|Disturbance in Attention||0.6||0.4||2.0||3.5|
|Gastroesophageal Reflux Disease||1.3||0.8||3.2||2.6|
|General Disorders and Administration Site Conditions|
|Skin and Subcutaneous Tissue Disorders|
|Metabolism and Nutrition Disorders|
|Reproductive System and Breast Disorders|
|Infections and Infestations|
|Upper Respiratory Tract Infection||12.8||15.8||12.2||13.5|
|Urinary Tract Infection||3.6||3.3||5.2||5.2|
|Musculoskeletal and Connective Tissue Disorders|
|Pain in Extremity||2.8||2.1||3.0||3.0|
|Respiratory, Thoracic, and Mediastinal Disorders|
|Injury, Poisoning, and Procedural Complications|
Reports of paresthesia, characterized as tingling in hands, feet, or face, occurred in 4.2%, 13.7%, and 19.9% of patients treated with Qsymia 3.75 mg/23 mg, 7.5 mg/46 mg, and 15 mg/92 mg, respectively, compared to 1.9% of patients treated with placebo. Dysgeusia was characterized as a metallic taste, and occurred in 1.3%, 7.4%, and 9.4% of patients treated with Qsymia 3.75 mg/23 mg, 7.5 mg/46 mg, and 15 mg/92 mg, respectively, compared to 1.1% of patients treated with placebo. The majority of these events first occurred within the initial 12 weeks of drug therapy; however, in some patients, events were reported later in the course of treatment. Only Qsymia-treated patients discontinued treatment due to these events (1% for paresthesia and 0.6% for dysgeusia).
Mood and Sleep Disorders
The proportion of patients in 1-year controlled trials of Qsymia reporting one or more adverse reactions related to mood and sleep disorders was 15.8%, 14.5%, and 20.6% with Qsymia 3.75 mg/23 mg, 7.5 mg/46 mg, and 15 mg/92 mg, respectively, compared to 10.3% with placebo. These events were further categorized into sleep disorders, anxiety, and depression. Reports of sleep disorders were typically characterized as insomnia, and occurred in 6.7%, 8.1%, and 11.1% of patients treated with Qsymia 3.75 mg/23 mg, 7.5 mg/46 mg, and 15 mg/92 mg, respectively, compared to 5.8% of patients treated with placebo. Reports of anxiety occurred in 4.6%, 4.8%, and 7.9% of patients treated with Qsymia 3.75 mg/23 mg, 7.5 mg/46 mg, and 15 mg/92 mg, respectively, compared to 2.6% of patients treated with placebo. Reports of depression/mood problems occurred in 5.0%, 3.8%, and 7.6% of patients treated with Qsymia 3.75 mg/23 mg, 7.5 mg/46 mg, and 15 mg/92 mg, respectively, compared to 3.4% of patients treated with placebo. The majority of these events first occurred within the initial 12 weeks of drug therapy; however, in some patients, events were reported later in the course of treatments. In the Qsymia clinical trials, the overall prevalence of mood and sleep adverse reactions was approximately twice as great in patients with a history of depression compared to patients without a history of depression; however, the proportion of patients on active treatment versus placebo who reported mood and sleep adverse reactions was similar in these two subgroups. Occurrence of depression-related events was more frequent in patients with a past history of depression across all treatment groups. However, the placebo-adjusted difference in incidence of these events remained constant between groups regardless of previous depression history.
In the 1-year controlled trials of Qsymia, the proportion of patients who experienced one or more cognitiverelated adverse reactions was 2.1% for Qsymia 3.75 mg/23 mg, 5.0% for Qsymia 7.5 mg/46 mg, and 7.6% for Qsymia 15 mg/92 mg, compared to 1.5% for placebo. These adverse reactions were comprised primarily of reports of problems with attention/concentration, memory, and language (word finding). These events typically began within the first 4 weeks of treatment, had a median duration of approximately 28 days or less, and were reversible upon discontinuation of treatment; however, individual patients did experience events later in treatment, and events of longer duration.
In the 1-year controlled trials of Qsymia, the incidence of persistent treatment-emergent decreases in serum bicarbonate below the normal range (levels of less than 21 mEq/L at 2 consecutive visits or at the final visit) was 8.8% for Qsymia 3.75 mg/23 mg, 6.4% for Qsymia 7.5 mg/46 mg, and 12.8% for Qsymia 15 mg/92 mg, compared to 2.1% for placebo.
The incidence of persistent, markedly low serum bicarbonate values (levels of less than 17 mEq/L on 2 consecutive visits or at the final visit) was 1.3% for Qsymia 3.75 mg/23 mg, 0.2% for Qsymia 7.5 mg/46 mg dose, and 0.7% for Qsymia 15 mg/92 mg dose, compared to 0.1% for placebo. Generally, decreases in serum bicarbonate levels were mild (average 1-3 mEq/L) and occurred early in treatment (4-week visit), however severe decreases and decreases later in treatment occurred.
In the 1-year controlled trials of Qsymia, the incidence of persistent low serum potassium values (less than 3.5 mEq/L at two consecutive visits or at the final visit) during the trial was 0.4% for Qsymia 3.75 mg/23 mg, 3.6% for Qsymia 7.5 mg/46 mg dose, and 4.9% for Qsymia 15 mg/92 mg, compared to 1.1% for placebo. Of the subjects who experienced persistent low serum potassium, 88% were receiving treatment with a nonpotassium sparing diuretic.
The incidence of markedly low serum potassium (less than 3 mEq/L, and a reduction from pre-treatment of greater than 0.5 mEq/L) at any time during the trial was 0.0% for Qsymia 3.75 mg/23 mg, 0.2% for Qsymia 7.5 mg/46 mg dose, and 0.7% for Qsymia 15 mg/92 mg dose, compared to 0.0% for placebo. Persistent markedly low serum potassium (less than 3 mEq/L, and a reduction from pre-treatment of greater than 0.5 mEq/L at two consecutive visits or at the final visit) occurred in 0.0% of subjects receiving Qsymia 3.75 mg/23 mg, 0.2% receiving Qsymia 7.5 mg/46 mg dose, and 0.1% receiving Qsymia 15 mg/92 mg dose, compared to 0.0% receiving placebo.
Hypokalemia was reported by 0.4% of subjects treated with Qsymia 3.75 mg/23 mg, 1.4% of subjects treated with Qsymia 7.5 mg/46 mg, and 2.5% of subjects treated with Qsymia 15 mg/92 mg compared to 0.4% of subjects treated with placebo. “Blood potassium decreased” was reported by 0.4% of subjects treated with Qsymia 3.75 mg/23 mg, 0.4% of subjects treated with Qsymia 7.5 mg/46 mg, and 1.0% of subjects treated with Qsymia 15 mg/92 mg 0.0% of subjects treated with placebo.
In the 1-year controlled trials of Qsymia, there was a dose-related increase from baseline, peaking between Week 4 to 8, which declined but remained elevated over baseline over 1 year of treatment. The incidence of increases in serum creatinine of greater than or equal to 0.3 mg/dL at any time during treatment was 2.1% for Qsymia 3.75 mg/23 mg, 7.2% for Qsymia 7.5 mg/46 mg, and 8.4% for Qsymia 15 mg/92 mg, compared to 2.0% for placebo. Increases in serum creatinine of greater than or equal to 50% over baseline occurred in 0.8% of subjects receiving Qsymia 3.75 mg/23 mg, 2.0% receiving Qsymia 7.5 mg/46 mg, and 2.8% receiving Qsymia 15 mg/92 mg, compared to 0.6% receiving placebo.
In the 1-year controlled trials of Qsymia, the incidence of nephrolithiasis was 0.4% for Qsymia 3.75 mg/23 mg, 0.2% for Qsymia 7.5 mg/46 mg, and 1.2% for Qsymia 15 mg/92 mg, compared to 0.3% for placebo.
Drug Discontinuation Due to Adverse Reactions
In the 1-year placebo-controlled clinical studies, 11.6% of Qsymia 3.75 mg/23 mg, 11.6% of Qsymia 7.5 mg/46 mg, 17.4% of Qsymia 15 mg/92 mg, and 8.4% of placebo-treated patients discontinued treatment due to reported adverse reactions. The most common adverse reactions that led to discontinuation of treatment are shown in Table 4.
Table 4: Adverse Reactions Greater Than or Equal To 1%
Leading to Treatment Discontinuation (1-Year Clinical Trials)
|Adverse Reaction Leading to Treatment Discontinuationa||Placebo
|Qsymia 3.75 mg/23 mg
|Qsymia 7.5 mg/46 mg
|Qsymia 15 mg/92 mg
|a greater than or equal to 1% in any treatment group|
The following adverse reactions have been reported during post approval use of phentermine and topiramate, the components of Qsymia. Because these reactions are reported voluntarily from a population of uncertain size it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure.
Allergic adverse reactions
Cardiovascular adverse reactions
Elevation of blood pressure, Ischemic events
Central nervous system adverse reactions
Euphoria, Psychosis, Tremor
Reproductive adverse reactions
Changes in libido, Impotence
Bullous skin reactions (including erythema multiforme, Stevens-Johnson syndrome, toxic epidermal necrolysis), Pemphigus
Hepatic failure (including fatalities), Hepatitis
Ophthalmic disorders Maculopathy
Read the entire FDA prescribing information for Qsymia (Phentermine and Topiramate) »
Additional Qsymia Information
- Qsymia Drug Interactions Center: phentermine-topiramate oral
- Qsymia Side Effects Center
- Qsymia FDA Approved Prescribing Information including Dosage
Report Problems to the Food and Drug Administration
You are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088.
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