Drug · FAERS side-effect profile with label screen
Phentermine and Topiramate side effects: what 5,789 FDA adverse event reports show
Drug class
Cytochrome P450 3A4 Inducers, Cytochrome P450 2C19 Inhibitors
FDA label (mechanism-of-action class)
Who reports
5,789 reports · 15% serious · 16 with death outcome · 89% female
openFDA FAERS counts, all years, deduplication not applied
Used for
Phentermine and topiramate extended-release capsules are indicated in combination with a reduced-calorie diet and increased physical activity to reduce excess body weight and maintain weight reduction long term in: Adults and pediatric patients aged 12.
FDA label, Indications and Usage
What it is
Phentermine and topiramate extended-release capsules are comprised of immediate-release phentermine hydrochloride (expressed as the weight of the free base) and extended-release topiramate. Ph.
FDA label, Description section
Boxed warning
None in the current label
How to read this page. FAERS is a spontaneous-reporting system: counts are not incidence rates and a signal is not proof of causation.
Each reaction below is run through an automated screen — is the term in the FDA label (known), in the indications (the disease being treated), an administrative/coding term, or none of these (unlabeled)?
That screen is mechanical text matching, not a causality assessment. The 30 hand-written Bradford Hill assessments are on the causality assessment page. Not medical advice.
Causality screen of the 40 strongest signals
Labeled adverse reaction 14Labeled (related wording) 8Likely indication confounding 1Reporting / coding artifact 5Lab value / disease marker 1Not in label — unassessed 11
What the badges mean
- Labeled adverse reaction The exact term appears in the label's warnings or adverse-reactions sections: a known, expected effect. The FAERS signal confirms the label rather than discovering anything.
- Labeled (related wording) The label describes this effect under different wording (e.g. 'neutropenia' for 'neutrophil count decreased'). Treated as known.
- Likely indication confounding The term appears in the label's indications: reports probably describe the disease being treated (or its progression), not a drug effect. Classic confounding by indication.
- Reporting / coding artifact An administrative, monitoring or exposure term (product issue, off-label use, 'test normal', overdose...). Not a biological reaction; a high PRR here reflects how reports are coded.
- Lab value / disease marker A laboratory result, investigation or disease-activity marker (antibody positive, CRP abnormal, swollen joint count) not described in the label. These usually mirror the monitored disease or testing protocol rather than a drug effect; not screened further.
- Not in label — unassessed Not found in the label text, not an artifact pattern. This is a genuine candidate for a formal causality assessment (Bradford Hill / WHO-UMC); it has NOT had one here.
Strongest disproportionality signals
Flagged terms (PRR ≥ 2, χ² ≥ 4, n ≥ 10), ranked by PRR; infinite PRRs (no comparator reports) excluded. The EBGM column is a second, shrinkage-based estimate (MGPS) with its 5th percentile EB05 and the BCPNN IC025; a pair flagged by PRR alone is marked PRR-only and should be read as fragile. The strata column recomputes the PRR on serious reports only and flags pairs whose reports are unusually skewed by sex or come mostly from consumers rather than clinicians. 93 further terms are in the interactive explorer. Reaction links open the term's cross-drug page.
Show:
| Reaction | Reports | PRR 95% CI · ROR · χ²/p | EBGM EB05 · IC025 | Label screen | Serious-only & strata | Trial cross-check |
|---|---|---|---|---|---|---|
| Hunger | 67 | 18.1 14.3–23.0ROR 18.3 · χ² 1,063 / p 2e-233 | 18.0 EB05 14.6 · IC025 +3.6 3/3 methods agree | Not in label — unassessed | serious n=2 · 97% consumer | no trial data cached |
| Pregnancy | 81 | 14.6 11.7–18.1ROR 14.8 · χ² 1,006 / p 4e-221 | 14.4 EB05 11.9 · IC025 +3.4 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 6.0 | no trial data cached |
| Dry mouth | 273 | 12.2 10.9–13.8ROR 12.8 · χ² 2,810 / p <1e-300 | 12.2 EB05 11.0 · IC025 +3.4 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 4.4 · 94% consumer | no trial data cached |
| Feeling jittery | 63 | 12.0 9.4–15.3ROR 12.1 · χ² 622 / p 1e-137 | 11.7 EB05 9.4 · IC025 +3.0 3/3 methods agree | Not in label — unassessed | serious n=6 · 97% consumer | no trial data cached |
| Brain fog | 44 | 11.0 8.2–14.7ROR 11.0 · χ² 387 / p 2e-86 | 10.5 EB05 8.0 · IC025 +2.8 3/3 methods agree | Not in label — unassessed | serious PRR 5.5 · 91% consumer | no trial data cached |
| Thyroid disorder | 45 | 10.6 7.9–14.2ROR 10.7 · χ² 381 / p 4e-85 | 10.2 EB05 7.8 · IC025 +2.8 3/3 methods agree | Labeled (related wording) related wording | serious PRR 2.5 · 100% consumer | no trial data cached |
| Taste disorder | 55 | 10.0 7.7–13.0ROR 10.1 · χ² 434 / p 1e-96 | 9.6 EB05 7.5 · IC025 +2.8 3/3 methods agree | Labeled (related wording) related wording | serious PRR 2.8 · 98% consumer | no trial data cached |
| Incorrect product administration duration | 46 | 8.2 6.2–11.0ROR 8.3 · χ² 284 / p 4e-64 | 7.8 EB05 6.0 · IC025 +2.4 3/3 methods agree | Reporting / coding artifact | serious n=6 · 96% consumer | no trial data cached |
| Increased appetite | 39 | 7.5 5.5–10.3ROR 7.6 · χ² 214 / p 9e-49 | 7.0 EB05 5.3 · IC025 +2.3 3/3 methods agree | Labeled (related wording) related wording | 87% consumer | no trial data cached |
| Paraesthesia (tingling/numbness) | 323 | 7.4 6.7–8.3ROR 7.8 · χ² 1,801 / p <1e-300 | 7.4 EB05 6.7 · IC025 +2.7 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 4.4 · 91% consumer | no trial data cached |
| Thirst | 36 | 7.3 5.3–10.2ROR 7.4 · χ² 190 / p 1e-43 | 6.8 EB05 5.1 · IC025 +2.2 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 5.7 · 100% consumer | no trial data cached |
| Dysgeusia (altered taste) | 125 | 6.1 5.1–7.2ROR 6.2 · χ² 525 / p 1e-116 | 5.9 EB05 5.1 · IC025 +2.3 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 5.7 · 96% consumer | no trial data cached |
| Ocular discomfort | 17 | 5.7 3.5–9.1ROR 5.7 · χ² 61 / p 3e-15 | 5.0 EB05 3.3 · IC025 +1.5 3/3 methods agree | Labeled (related wording) related wording | serious n=3 | no trial data cached |
| Intraocular pressure increased (raised eye pressure) | 20 | 5.6 3.6–8.8ROR 5.7 · χ² 72 / p 1e-17 | 5.0 EB05 3.4 · IC025 +1.6 3/3 methods agree | Lab value / disease marker | serious PRR 14.3 · 85% consumer | no trial data cached |
| Hypothyroidism | 49 | 5.6 4.2–7.4ROR 5.6 · χ² 180 / p 3e-41 | 5.3 EB05 4.2 · IC025 +1.9 3/3 methods agree | Labeled (related wording) related wording | serious PRR 14.8 · 92% consumer | no trial data cached |
| Mood altered | 41 | 5.5 4.0–7.4ROR 5.5 · χ² 145 / p 9e-34 | 5.2 EB05 4.0 · IC025 +1.9 3/3 methods agree | Not in label — unassessed | serious PRR 3.6 · 90% consumer | no trial data cached |
| Irritability | 79 | 4.8 3.8–5.9ROR 4.8 · χ² 231 / p 2e-52 | 4.6 EB05 3.8 · IC025 +1.8 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 2.4 · 93% consumer | no trial data cached |
| Palpitations (pounding heartbeat) | 151 | 4.7 4.0–5.5ROR 4.8 · χ² 435 / p 6e-97 | 4.6 EB05 4.0 · IC025 +1.9 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 2.2 · 91% consumer | no trial data cached |
| Disturbance in attention | 69 | 4.6 3.7–5.8ROR 4.7 · χ² 193 / p 4e-44 | 4.5 EB05 3.7 · IC025 +1.8 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 5.3 · 89% consumer | no trial data cached |
| Glaucoma | 23 | 4.3 2.9–6.5ROR 4.3 · χ² 56 / p 5e-14 | 4.0 EB05 2.8 · IC025 +1.3 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 13.9 · 75% consumer | no trial data cached |
| Weight increased (weight gain) | 262 | 4.3 3.8–4.8ROR 4.4 · χ² 658 / p 3e-145 | 4.2 EB05 3.8 · IC025 +1.9 3/3 methods agree | Likely indication confounding term in indications; also in warnings | serious PRR 2.2 · 91% consumer | no trial data cached |
| Adverse drug reaction | 102 | 4.1 3.4–5.0ROR 4.2 · χ² 240 / p 2e-54 | 4.1 EB05 3.4 · IC025 +1.7 3/3 methods agree | Reporting / coding artifact | 95% consumer | no trial data cached |
| Seasonal allergy | 16 | 4.1 2.5–6.7ROR 4.1 · χ² 35 / p 2e-9 | 3.7 EB05 2.4 · IC025 +1.1 3/3 methods agree | Not in label — unassessed | serious n=2 | no trial data cached |
| Vision blurred (blurred vision) | 153 | 4.1 3.5–4.7ROR 4.1 · χ² 352 / p 9e-79 | 4.0 EB05 3.5 · IC025 +1.7 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 4.6 · 89% consumer | no trial data cached |
| Inappropriate schedule of product administration | 195 | 4.0 3.5–4.6ROR 4.1 · χ² 439 / p 1e-97 | 4.0 EB05 3.5 · IC025 +1.8 3/3 methods agree | Reporting / coding artifact | serious PRR 0.2 · 95% consumer | no trial data cached |
| Nephrolithiasis (kidney stones) | 49 | 3.9 2.9–5.1ROR 3.9 · χ² 102 / p 3e-24 | 3.8 EB05 3.0 · IC025 +1.4 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 10.3 · 74% consumer | no trial data cached |
| Mental impairment | 26 | 3.9 2.6–5.7ROR 3.9 · χ² 53 / p 2e-13 | 3.7 EB05 2.6 · IC025 +1.2 3/3 methods agree | Labeled (related wording) related wording | serious PRR 2.9 · 96% consumer | no trial data cached |
| Hypoaesthesia oral | 16 | 3.9 2.4–6.3ROR 3.9 · χ² 31 / p 1e-8 | 3.5 EB05 2.3 · IC025 +1.0 3/3 methods agree | Not in label — unassessed | serious PRR 1.7 | no trial data cached |
| Insomnia (trouble sleeping) | 277 | 3.8 3.4–4.2ROR 3.9 · χ² 566 / p 2e-125 | 3.7 EB05 3.4 · IC025 +1.7 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 2.2 · 96% consumer | no trial data cached |
| Mood swings | 30 | 3.4 2.4–4.9ROR 3.4 · χ² 49 / p 1e-12 | 3.3 EB05 2.4 · IC025 +1.1 3/3 methods agree | Not in label — unassessed | serious PRR 3.8 · 82% consumer | no trial data cached |
| Hypoaesthesia (numbness) | 140 | 3.4 2.9–4.0ROR 3.4 · χ² 234 / p 3e-53 | 3.4 EB05 2.9 · IC025 +1.5 3/3 methods agree | Not in label — unassessed | serious PRR 2.8 · 93% consumer | no trial data cached |
| Constipation | 201 | 3.4 2.9–3.9ROR 3.5 · χ² 335 / p 4e-75 | 3.3 EB05 3.0 · IC025 +1.5 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 2.3 · 96% consumer | no trial data cached |
| Heart rate increased | 91 | 3.3 2.7–4.1ROR 3.4 · χ² 147 / p 5e-34 | 3.3 EB05 2.8 · IC025 +1.4 3/3 methods agree | Labeled (related wording) related wording | serious PRR 2.3 · 92% consumer | no trial data cached |
| Feeling abnormal | 218 | 3.3 2.9–3.7ROR 3.4 · χ² 348 / p 6e-78 | 3.3 EB05 2.9 · IC025 +1.5 3/3 methods agree | Not in label — unassessed | serious PRR 2.0 · 93% consumer | no trial data cached |
| Aphasia (loss of speech) | 27 | 3.2 2.2–4.7ROR 3.2 · χ² 39 / p 2e-10 | 3.1 EB05 2.2 · IC025 +1.0 3/3 methods agree | Not in label — unassessed | serious PRR 2.2 · 93% consumer | no trial data cached |
| Alopecia (hair loss) | 174 | 3.2 2.8–3.7ROR 3.3 · χ² 264 / p 1e-59 | 3.2 EB05 2.8 · IC025 +1.4 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 1.8 · 84% consumer | no trial data cached |
| Nervousness | 46 | 3.2 2.4–4.2ROR 3.2 · χ² 66 / p 2e-16 | 3.1 EB05 2.4 · IC025 +1.1 3/3 methods agree | Not in label — unassessed | serious PRR 3.2 · 95% consumer | no trial data cached |
| Intentional dose omission | 22 | 2.9 1.9–4.4ROR 2.9 · χ² 26 / p 2e-7 | 2.8 EB05 2.0 · IC025 +0.8 | Reporting / coding artifact | serious PRR 1.0 | no trial data cached |
| Thinking abnormal | 15 | 2.9 1.8–4.8ROR 2.9 · χ² 17 / p 2e-5 | 2.7 EB05 1.8 · IC025 +0.6 | Labeled (related wording) related wording | serious PRR 2.3 | no trial data cached |
| Adverse event | 72 | 2.8 2.3–3.6ROR 2.9 · χ² 84 / p 3e-20 | 2.8 EB05 2.3 · IC025 +1.1 3/3 methods agree | Reporting / coding artifact | serious PRR 1.4 · 93% consumer | no trial data cached |
Trial evidence (ClinicalTrials.gov)
Trial cross-check not yet run for this drug (ClinicalTrials.gov pull covers the 800 most-reported drugs first).
Most frequently reported reactions
By raw co-report count, regardless of disproportionality. Common terms here are often the illness itself or generic outcomes.
| Reaction | Reports | PRR 95% CI · ROR · χ²/p | EBGM EB05 · IC025 | Label screen | Serious-only & strata | Trial cross-check |
|---|---|---|---|---|---|---|
| Headache | 362 | 2.1 1.9–2.3ROR 2.2 · χ² 212 / p 2e-48 | 2.1 EB05 1.9 · IC025 +0.9 | Labeled adverse reaction exact term | serious PRR 1.7 · 93% consumer | no trial data cached |
| Paraesthesia (tingling/numbness) | 323 | 7.4 6.7–8.3ROR 7.8 · χ² 1,801 / p <1e-300 | 7.4 EB05 6.7 · IC025 +2.7 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 4.4 · 91% consumer | no trial data cached |
| Insomnia (trouble sleeping) | 277 | 3.8 3.4–4.2ROR 3.9 · χ² 566 / p 2e-125 | 3.7 EB05 3.4 · IC025 +1.7 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 2.2 · 96% consumer | no trial data cached |
| Dry mouth | 273 | 12.2 10.9–13.8ROR 12.8 · χ² 2,810 / p <1e-300 | 12.2 EB05 11.0 · IC025 +3.4 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 4.4 · 94% consumer | no trial data cached |
| Dizziness | 262 | 1.9 1.7–2.1ROR 1.9 · χ² 115 / p 5e-27 | 1.9 EB05 1.7 · IC025 +0.7 | Labeled adverse reaction exact term | serious PRR 1.0 · 88% consumer | no trial data cached |
| Weight increased (weight gain) | 262 | 4.3 3.8–4.8ROR 4.4 · χ² 658 / p 3e-145 | 4.2 EB05 3.8 · IC025 +1.9 3/3 methods agree | Likely indication confounding term in indications; also in warnings | serious PRR 2.2 · 91% consumer | no trial data cached |
| Feeling abnormal | 218 | 3.3 2.9–3.7ROR 3.4 · χ² 348 / p 6e-78 | 3.3 EB05 2.9 · IC025 +1.5 3/3 methods agree | Not in label — unassessed | serious PRR 2.0 · 93% consumer | no trial data cached |
| Constipation | 201 | 3.4 2.9–3.9ROR 3.5 · χ² 335 / p 4e-75 | 3.3 EB05 3.0 · IC025 +1.5 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 2.3 · 96% consumer | no trial data cached |
| Inappropriate schedule of product administration | 195 | 4.0 3.5–4.6ROR 4.1 · χ² 439 / p 1e-97 | 4.0 EB05 3.5 · IC025 +1.8 3/3 methods agree | Reporting / coding artifact | serious PRR 0.2 · 95% consumer | no trial data cached |
| Anxiety | 186 | 2.4 2.1–2.7ROR 2.4 · χ² 147 / p 5e-34 | 2.4 EB05 2.1 · IC025 +1.0 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 1.5 · 90% consumer | no trial data cached |
| Alopecia (hair loss) | 174 | 3.2 2.8–3.7ROR 3.3 · χ² 264 / p 1e-59 | 3.2 EB05 2.8 · IC025 +1.4 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 1.8 · 84% consumer | no trial data cached |
| Depression | 153 | 2.4 2.1–2.8ROR 2.5 · χ² 128 / p 5e-30 | 2.4 EB05 2.1 · IC025 +1.0 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 2.7 · 86% consumer | no trial data cached |
| Vision blurred (blurred vision) | 153 | 4.1 3.5–4.7ROR 4.1 · χ² 352 / p 9e-79 | 4.0 EB05 3.5 · IC025 +1.7 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 4.6 · 89% consumer | no trial data cached |
| Palpitations (pounding heartbeat) | 151 | 4.7 4.0–5.5ROR 4.8 · χ² 435 / p 6e-97 | 4.6 EB05 4.0 · IC025 +1.9 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 2.2 · 91% consumer | no trial data cached |
| Product dose omission issue | 145 | 1.8 1.6–2.2ROR 1.9 · χ² 56 / p 4e-14 | 1.8 EB05 1.6 · IC025 +0.6 | Reporting / coding artifact | serious PRR 1.3 · 95% consumer | no trial data cached |
Unlabeled candidate signals
These flagged terms were not found in the FDA label text and do not match an artifact pattern. They are the pairs that would merit a structured assessment (temporality, dose-response, biological plausibility, consistency across databases, trial or cohort evidence). The screen has not done that; string-matching misses label wording, and a strong PRR can still be stimulated reporting, co-medication, or the disease itself.
- Hunger — n=67, PRR 18.1
- Feeling jittery — n=63, PRR 12.0
- Brain fog — n=44, PRR 11.0
- Mood altered — n=41, PRR 5.5
- Mood swings — n=30, PRR 3.4
- Hypoaesthesia — n=140, PRR 3.4
- Feeling abnormal — n=218, PRR 3.3
- Aphasia — n=27, PRR 3.2
- Nervousness — n=46, PRR 3.2
✓ A hand-written Bradford Hill causality assessment exists for this drug: Phentermine ↔ Tachycardia.
Want to assess one of these properly? The runbook describes the Bradford Hill / trial-evidence workflow used on the assessment page, and handoff_top1000_signals.csv lists the strongest unassessed pairs across all drugs.
Common questions
What are the most reported side effects of Phentermine and Topiramate?
In FDA FAERS, the most frequently co-reported reaction terms for Phentermine and Topiramate are headache, paraesthesia, insomnia, dry mouth, dizziness, weight increased. These are report counts, not rates: FAERS has no denominator, reporting is voluntary and uneven, and a term can be reported because of the illness being treated rather than the drug.
Does Phentermine and Topiramate have an FDA boxed warning?
No. The FDA label retrieved for Phentermine and Topiramate has no boxed warning; see the label's Warnings and Precautions for the recognised risks.
Do FAERS signals prove that Phentermine and Topiramate causes these side effects?
No. A disproportionality signal (PRR, ROR) means a reaction is reported more often with this drug than with others in the database. That can reflect a real effect, but also the disease being treated, stimulated reporting after news or litigation, co-medications, or how reports are coded. Causality needs temporality, dose-response, biological plausibility, consistency across data sources and, ideally, trial or cohort evidence. This page screens each term against the FDA label and ClinicalTrials.gov results; it does not establish causation.
Sources & methods
- FDA label via openFDA (set ID 876bd763-13fa-481e-b579-c2fc44dbf3c2, effective 20260518; matched on
openfda.generic_name.exact:"PHENTERMINE AND TOPIRAMATE") - Bayesian shrinkage measures computed offline over all 1,317,300 cached pairs: BCPNN information component (IC, with Norén closed-form IC025) and MGPS empirical-Bayes geometric mean (EBGM, EB05) with a two-component gamma prior fitted by maximum marginal likelihood (α₁=0.57, β₁=0.02, α₂=1.42, β₂=0.70, w=0.17); unstratified
- FAERS pair statistics from the OpenPV build of 2026-09-14 (openFDA
count=aggregation, fieldpatient.drug.openfda.generic_name.exact, 133 reaction terms, min 3 co-reports); PRR/ROR with 95% CI, chi-square with Yates correction - Serious-only and stratified counts (serious:1, patient.patientsex, primarysource.qualification) from openFDA count queries; serious-only PRR uses the drug serious report total and the term global serious total (N_serious=11,882,979); strata shown only when n ≥ 20
- Seriousness and sex counts from openFDA
count=serious,patient.patientsex,seriousnessdeath
Page generated 2026-10-08. Label and PubChem text are retrieved automatically and may lag the current label; always check the current prescribing information. OpenPV is a beta research tool of the Open Source Medicine Foundation.