Short answer: In the label's 1-year adult trials, the side effects most clearly above placebo were paraesthesia (tingling, 4% to 20% vs 2%), dry mouth (7% to 19% vs 3%), constipation (8% to 16% vs 6%), dysgeusia (taste change), insomnia and dizziness, rising with dose. Qsymia has no boxed warning, but it can cause birth defects and is sold only through certified pharmacies under a REMS program.
What Qsymia is approved for: Qsymia is approved, with a reduced-calorie diet and more physical activity, to reduce excess body weight and keep it off long term in adults and children 12 and older with obesity, and in adults with overweight and at least one weight-related condition (section 1). The label says its effect on heart disease and death has not been established. Phentermine is a Schedule IV controlled substance (section 9.1).
Source
QSYMIA (phentermine and topiramate extended-release capsules), for oral use, CIV, prescribing information and Medication Guide. VIVUS. DailyMed, version published April 24, 2026. DailyMed setid 40dd5602-53da-45ac-bb4b-15789aba40f9
No. The current Qsymia label has no boxed warning.
These are the label's own numbers from the Adverse Reactions section. Where the label compares with placebo (a dummy treatment), both columns are shown, so you can see how much more often a reaction happened on Qsymia.
| Adverse reaction | 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 = 1,580) % |
|---|---|---|---|---|
| Paraesthesia | 2 | 4 | 14 | 20 |
| Dry Mouth | 3 | 7 | 14 | 19 |
| Constipation | 6 | 8 | 15 | 16 |
| Upper Respiratory Tract Infection | 13 | 16 | 12 | 14 |
| Headache | 9 | 10 | 7 | 11 |
| Dysgeusia | 1 | 1 | 7 | 9 |
| Insomnia | 5 | 5 | 6 | 9 |
| Nasopharyngitis | 8 | 13 | 11 | 9 |
| Dizziness | 3 | 3 | 7 | 9 |
| Sinusitis | 6 | 8 | 7 | 8 |
| Nausea | 4 | 6 | 4 | 7 |
| Back Pain | 5 | 5 | 6 | 7 |
| Fatigue | 4 | 5 | 4 | 6 |
| Diarrhea | 5 | 5 | 6 | 6 |
| Vision Blurred | 4 | 6 | 4 | 5 |
| Bronchitis | 4 | 7 | 4 | 5 |
| Urinary Tract Infection | 4 | 3 | 5 | 5 |
| Cough | 4 | 3 | 4 | 5 |
| Influenza | 4 | 8 | 5 | 4 |
| Depression | 2 | 3 | 3 | 4 |
| Anxiety | 2 | 3 | 2 | 4 |
| Hypoesthesia | 1 | 1 | 4 | 4 |
| Irritability | 1 | 2 | 3 | 4 |
| Alopecia | 1 | 2 | 3 | 4 |
| Disturbance in Attention | 1 | 0 | 2 | 4 |
| Pain in Extremity | 3 | 2 | 3 | 3 |
| Muscle Spasms | 2 | 3 | 3 | 3 |
| Dyspepsia | 2 | 2 | 2 | 3 |
| Gastroesophageal Reflux Disease | 1 | 1 | 3 | 3 |
| Rash | 2 | 2 | 2 | 3 |
| Hypokalemia | 0 | 0 | 1 | 3 |
| Dry Eye | 1 | 1 | 1 | 3 |
| Gastroenteritis | 2 | 1 | 2 | 3 |
| Pharyngolaryngeal Pain | 2 | 3 | 1 | 2 |
| Paraesthesia Oral | 0 | 0 | 1 | 2 |
| Eye Pain | 1 | 2 | 2 | 2 |
| Nasal Congestion | 1 | 2 | 1 | 2 |
| Thirst | 1 | 2 | 2 | 2 |
| Sinus Congestion | 2 | 3 | 3 | 2 |
| Procedural Pain | 2 | 2 | 2 | 2 |
| Palpitations | 1 | 1 | 2 | 2 |
| Musculoskeletal Pain | 1 | 1 | 3 | 2 |
| Decreased Appetite | 1 | 2 | 2 | 2 |
| Neck Pain | 1 | 1 | 2 | 1 |
| Dysmenorrhea | 0 | 2 | 0 | 1 |
| Chest Discomfort | 0 | 2 | 0 | 1 |
Two 1-year placebo-controlled trials and two supportive trials in 2,318 adults with overweight or obesity on Qsymia for a mean of 298 days. Reactions at 5% or more and at least 1.5 times placebo were paraesthesia, dizziness, dysgeusia, insomnia, constipation and dry mouth.
| Adverse reaction | Placebo (N = 56) % | QSYMIA 7.5 mg/46 mg (N = 54) % | QSYMIA 15 mg/92 mg (N = 113) % |
|---|---|---|---|
| Depression | 0 | 2 | 4 |
| Nausea | 4 | 4 | 4 |
| Pyrexia | 2 | 2 | 4 |
| Dizziness | 0 | 2 | 4 |
| Arthralgia | 0 | 2 | 4 |
| Paraesthesia | 0 | 2 | 3 |
| Anxiety | 0 | 2 | 3 |
| Abdominal Pain Upper | 0 | 0 | 3 |
| Fatigue | 2 | 0 | 3 |
| Ear Infection | 0 | 2 | 3 |
| Musculoskeletal Chest Pain | 0 | 0 | 3 |
| Influenza | 0 | 4 | 2 |
| Ligament Sprain | 0 | 4 | 2 |
One 56-week placebo-controlled trial of 223 children aged 12 to 17 with obesity.
| Increase from baseline | Placebo N=1561 n (%) | QSYMIA 3.75 mg/23 mg N=240 n (%) | QSYMIA 7.5 mg/46 mg N=498 n (%) | QSYMIA 15 mg/92 mg N=1580 n (%) |
|---|---|---|---|---|
| Greater than 5 bpm | 1021 (65.4) | 168 (70.0) | 372 (74.7) | 1228 (77.7) |
| Greater than 10 bpm | 657 (42.1) | 120 (50.0) | 251 (50.4) | 887 (56.1) |
| Greater than 15 bpm | 410 (26.3) | 79 (32.9) | 165 (33.1) | 590 (37.3) |
| Greater than 20 bpm | 186 (11.9) | 36 (15.0) | 67 (13.5) | 309 (19.6) |
In an 8-week 24-hour monitoring study in adults, Qsymia raised average heart rate by 3.6 beats per minute compared with placebo.
Tingling (paraesthesia) was described as tingling in the hands, feet or face, and dysgeusia as a metallic taste. 1% of adults stopped because of tingling and 0.6% because of taste change.
Mood and sleep reactions in adults: 15% on 7.5 mg/46 mg and 21% on 15 mg/92 mg vs 10% on placebo. Insomnia 8.1% and 11% vs 5.8%; anxiety 4.8% and 7.9% vs 2.6%; depression or mood problems 3.8% and 7.6% vs 3.4%.
Thinking-related reactions (attention, memory, word-finding): 5.0% on 7.5 mg/46 mg and 7.6% on 15 mg/92 mg vs 1.5% on placebo.
Kidney stones: 0.2% on 7.5 mg/46 mg and 1.2% on 15 mg/92 mg vs 0.3% on placebo.
Persistently low bicarbonate (under 21 mEq/L): 6.4% and 12.8% vs 2.1% on placebo. Persistently low potassium (under 3.5 mEq/L): 3.6% and 4.9% vs 1.1%; 88% of those were on a non-potassium-sparing diuretic. Creatinine rise of 0.3 mg/dL or more: 7.2% and 8.4% vs 2.0%.
In children 12 to 17, height gain was 1.3 to 1.4 cm/year slower than on placebo over 56 weeks, and bone density gains were smaller. 60% to 70% of children on Qsymia had persistently low bicarbonate vs 43% on placebo.
The Warnings and Precautions part of the label lists these. Each line gives the label's heading and what it means in plain words.
Birth defects. Qsymia can harm an unborn baby. Topiramate in the first trimester raises the risk of cleft lip or palate and of being small for gestational age. A negative pregnancy test is recommended before starting and every month during treatment, with effective birth control. Because of this, Qsymia is only available from certified pharmacies under the Qsymia REMS program.
Suicidal thoughts and behavior. Antiepileptic drugs, including topiramate, roughly doubled the risk of suicidal thoughts or behavior in pooled studies (0.43% vs 0.24%). In the Qsymia trial in children, 1 of 167 (0.6%) had suicidal thoughts needing hospital care. Qsymia is stopped if these occur and is avoided in people with past suicide attempts or active suicidal thoughts.
Eye problems. Topiramate can cause sudden nearsightedness with secondary angle-closure glaucoma, usually within the first month, with blurred vision or eye pain. The main treatment is stopping Qsymia as quickly as possible. Visual field loss has also been reported. Qsymia is not used by people with glaucoma.
Mood and sleep problems. Qsymia can cause depression, anxiety and insomnia. A lower dose or stopping may be considered if symptoms are significant or persist.
Thinking problems. Qsymia can affect concentration, memory and word-finding, more so with fast dose increases. Alcohol and other sedating drugs can add to dizziness and drowsiness. The label cautions about driving until people know how Qsymia affects them, and against excessive alcohol.
Slower growth in children. Children 12 to 17 on Qsymia grew 1.3 to 1.4 cm/year less than on placebo. Height is monitored.
Metabolic acidosis. Qsymia can lower blood bicarbonate. Long-term untreated acidosis can raise the risk of kidney stones, soft bones and fractures. Electrolytes are measured before and during treatment.
Kidney function. Creatinine can rise, peaking after 4 to 8 weeks, reflecting a drop in kidney filtration. It is measured before and during treatment.
Seizures if stopped suddenly. Stopping topiramate abruptly has caused seizures even in people without epilepsy. The 15 mg/92 mg dose is tapered rather than stopped at once.
Kidney stones. Qsymia is linked to kidney stones. Drinking more fluids is advised, and other carbonic anhydrase inhibitors are avoided.
Decreased sweating and overheating. Topiramate can reduce sweating and raise body temperature, sometimes needing hospital care, mostly in children and in hot weather.
Low potassium. Qsymia can lower potassium, more so with non-potassium-sparing diuretics. Potassium is measured before and during treatment.
DRESS and serious skin and allergic reactions. Topiramate has been linked to DRESS (a multiorgan allergic reaction), Stevens-Johnson syndrome, toxic epidermal necrolysis, anaphylaxis and angioedema (sections 5.13 to 5.15). Qsymia is stopped at the first sign of rash unless clearly unrelated.
FD&C Yellow No. 5. Qsymia contains tartrazine, which can cause allergic-type reactions including asthma in some people, especially those allergic to aspirin.
From the Medication Guide that comes with Qsymia:
Dose Track has a side-effect log. Each entry records the symptom, a severity (none, mild, moderate, severe or life-threatening), the date and an optional note, and can be tied to a specific dose or logged on its own. The history screen shows what you logged over time, which makes it easier to tell your prescriber when a reaction started and whether it is easing. The app records what you enter; it does not judge whether a symptom is serious. For anything on the label's call-your-doctor list, call your doctor.
This page is what the FDA label says, in plain words. It is not medical advice. Follow your prescriber, and ask them or your pharmacist about anything here.