Phenelzine side effects: what 1,563 FDA adverse event reports show
Drug class
Not stated in label
Label matched
Phenelzine Sulfate (Phenelzine Sulfate)
Who reports
1,563 reports · 57% serious · 41 with death outcome · 61% female
Used for
Phenelzine Sulfate Tablets, USP has been found to be effective in depressed patients clinically characterized as "atypical," "nonendogenous," or "neurotic." These patients often have mixed anxiety and depression and phobic or hypochondriacal features. There is less conclusive evidence of its usefulness with severely depressed patients with endogenous features.
What it is
DESCRIPTION Phenelzine Sulfate Tablets, USP (phenelzine sulfate) is a potent inhibitor of monoamine oxidase (MAO). Phenelzine sulfate is a hydrazine derivative. It has a molecular weight of 234.27 and is chemically described as C 8 H 12 N 2 • H 2 SO 4 .
Boxed warning
Suicidality and Antidepressant Drugs Antidepressants increased the risk compared to placebo of suicidal thinking and behavior (suicidality) in children, adolescents, and young adults in short-term studies of major depressive disorder (MDD) and other psychiatric disorders.
Causality screen of the 39 strongest signals
What the badges mean
- Labeled — boxed warning The term (or its clinical synonym) appears in the FDA boxed warning: causality is regulator-recognised and considered serious.
- 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.
- 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.
- 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. 36 further terms are in the interactive explorer. Reaction links open the term's cross-drug page.
| Reaction | Reports | PRR 95% CI · ROR · χ²/p | EBGM EB05 · IC025 | Label screen | Serious-only & strata | Trial cross-check |
|---|---|---|---|---|---|---|
| Pharmaceutical product complaint | 97 | 49.6 40.9–60.2ROR 52.8 · χ² 4,558 / p <1e-300 | 49.0 EB05 41.3 · IC025 +5.0 3/3 methods agree | Not in label — unassessed | serious PRR 74.6 | no trial data cached |
| Hypertensive crisis | 35 | 42.2 30.4–58.6ROR 43.1 · χ² 1,363 / p 1e-298 | 41.2 EB05 31.0 · IC025 +4.2 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 42.5 | no trial data cached |
| Serotonin syndrome | 36 | 25.3 18.3–34.9ROR 25.9 · χ² 815 / p 1e-179 | 25.0 EB05 18.8 · IC025 +3.7 3/3 methods agree | Labeled (related wording) related wording | serious PRR 25.6 · ♀ 83% (drug 61%) | no trial data cached |
| Orthostatic hypotension (dizziness on standing) | 22 | 16.9 11.2–25.6ROR 17.2 · χ² 314 / p 2e-70 | 16.5 EB05 11.2 · IC025 +2.9 3/3 methods agree | Not in label — unassessed | serious PRR 16.7 · ♀ 82% (drug 61%) | no trial data cached |
| Mania | 19 | 15.5 9.9–24.3ROR 15.7 · χ² 244 / p 3e-55 | 14.9 EB05 9.7 · IC025 +2.7 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 13.2 | no trial data cached |
| Panic attack | 42 | 15.5 11.5–20.8ROR 15.9 · χ² 554 / p 8e-123 | 15.3 EB05 11.7 · IC025 +3.2 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 18.8 | no trial data cached |
| Body height decreased | 11 | 13.7 7.6–24.6ROR 13.8 · χ² 117 / p 2e-27 | 12.0 EB05 6.2 · IC025 +2.1 3/3 methods agree | Not in label — unassessed | serious n=8 | no trial data cached |
| Euphoric mood | 10 | 13.0 7.0–24.2ROR 13.1 · χ² 99 / p 1e-23 | 11.1 EB05 5.6 · IC025 +2.0 3/3 methods agree | Not in label — unassessed | serious n=5 | no trial data cached |
| Muscle rigidity | 10 | 11.2 6.1–20.8ROR 11.3 · χ² 83 / p 4e-20 | 9.1 EB05 4.7 · IC025 +1.8 3/3 methods agree | Labeled (related wording) related wording | serious PRR 12.7 | no trial data cached |
| Withdrawal syndrome | 35 | 11.1 8.0–15.4ROR 11.4 · χ² 313 / p 2e-70 | 10.6 EB05 7.8 · IC025 +2.7 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 10.6 · 74% consumer | no trial data cached |
| Depression | 187 | 11.0 9.6–12.6ROR 12.3 · χ² 1,705 / p <1e-300 | 10.9 EB05 9.6 · IC025 +3.2 3/3 methods agree | Labeled — boxed warning exact term | serious PRR 12.4 · 74% consumer | no trial data cached |
| Drug effect decreased | 43 | 10.6 7.9–14.2ROR 10.8 · χ² 363 / p 2e-81 | 10.1 EB05 7.7 · IC025 +2.7 3/3 methods agree | Reporting / coding artifact | serious PRR 22.1 · ♀ 40% (drug 61%) · 85% consumer | no trial data cached |
| Crying | 25 | 9.2 6.2–13.6ROR 9.3 · χ² 175 / p 3e-40 | 8.4 EB05 5.8 · IC025 +2.3 3/3 methods agree | Not in label — unassessed | serious PRR 13.2 · ♀ 100% (drug 61%) · 76% consumer | no trial data cached |
| Nightmare | 23 | 8.9 5.9–13.3ROR 9.0 · χ² 153 / p 2e-35 | 8.0 EB05 5.4 · IC025 +2.2 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 12.5 | no trial data cached |
| Drug interaction | 100 | 8.5 7.0–10.2ROR 9.0 · χ² 655 / p 1e-144 | 8.2 EB05 6.9 · IC025 +2.7 3/3 methods agree | Reporting / coding artifact | serious PRR 7.9 | no trial data cached |
| Erectile dysfunction | 15 | 7.8 4.7–12.9ROR 7.9 · χ² 83 / p 5e-20 | 6.6 EB05 4.1 · IC025 +1.8 3/3 methods agree | Not in label — unassessed | serious PRR 8.3 | no trial data cached |
| Suicidal ideation (thoughts of suicide) | 51 | 7.5 5.7–9.8ROR 7.7 · χ² 280 / p 3e-63 | 7.1 EB05 5.6 · IC025 +2.3 3/3 methods agree | Labeled — boxed warning exact term | serious PRR 7.8 | no trial data cached |
| Fear | 15 | 7.4 4.5–12.3ROR 7.5 · χ² 77 / p 8e-19 | 6.3 EB05 4.0 · IC025 +1.7 3/3 methods agree | Not in label — unassessed | serious PRR 6.8 | no trial data cached |
| Weight increased (weight gain) | 122 | 7.4 6.2–8.7ROR 7.9 · χ² 670 / p 6e-148 | 7.2 EB05 6.2 · IC025 +2.5 3/3 methods agree | Labeled (related wording) related wording | serious PRR 9.9 · 73% consumer | no trial data cached |
| Activities of daily living impaired | 11 | 7.4 4.1–13.2ROR 7.4 · χ² 54 / p 9e-14 | 5.9 EB05 3.4 · IC025 +1.5 3/3 methods agree | Not in label — unassessed | serious PRR 9.0 | no trial data cached |
| Impaired work ability | 11 | 6.9 3.8–12.4ROR 6.9 · χ² 50 / p 9e-13 | 5.5 EB05 3.3 · IC025 +1.4 3/3 methods agree | Not in label — unassessed | serious PRR 5.6 | no trial data cached |
| Drug withdrawal syndrome | 44 | 6.7 5.0–8.9ROR 6.8 · χ² 207 / p 4e-47 | 6.3 EB05 4.8 · IC025 +2.1 3/3 methods agree | Labeled (related wording) related wording | serious PRR 6.1 · 76% consumer | no trial data cached |
| Nervousness | 25 | 6.4 4.3–9.4ROR 6.5 · χ² 109 / p 1e-25 | 5.8 EB05 4.1 · IC025 +1.9 3/3 methods agree | Not in label — unassessed | serious PRR 10.0 · 75% consumer | no trial data cached |
| Amnesia (memory loss) | 31 | 6.4 4.5–9.0ROR 6.5 · χ² 135 / p 1e-31 | 5.9 EB05 4.3 · IC025 +2.0 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 7.8 · 74% consumer | no trial data cached |
| Product prescribing error | 11 | 6.2 3.5–11.2ROR 6.3 · χ² 43 / p 2e-11 | 5.1 EB05 3.0 · IC025 +1.3 3/3 methods agree | Reporting / coding artifact | serious PRR 13.1 | no trial data cached |
| Psychotic disorder | 13 | 5.9 3.4–10.1ROR 5.9 · χ² 48 / p 2e-12 | 5.0 EB05 3.1 · IC025 +1.4 3/3 methods agree | Not in label — unassessed | serious PRR 6.5 | no trial data cached |
| Ageusia (loss of taste) | 10 | 5.4 2.9–10.0ROR 5.4 · χ² 31 / p 1e-8 | 4.4 EB05 2.6 · IC025 +1.1 3/3 methods agree | Not in label — unassessed | serious PRR 8.3 | no trial data cached |
| Contraindicated product administered | 12 | 5.3 3.0–9.4ROR 5.4 · χ² 38 / p 3e-10 | 4.5 EB05 2.8 · IC025 +1.2 3/3 methods agree | Reporting / coding artifact | serious PRR 6.7 | no trial data cached |
| Abnormal dreams | 11 | 5.3 2.9–9.6ROR 5.3 · χ² 34 / p 2e-9 | 4.4 EB05 2.7 · IC025 +1.1 3/3 methods agree | Not in label — unassessed | serious PRR 10.5 | no trial data cached |
| Agitation | 28 | 5.1 3.5–7.4ROR 5.2 · χ² 89 / p 2e-21 | 4.7 EB05 3.4 · IC025 +1.6 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 5.1 | no trial data cached |
| Gastric disorder | 13 | 5.0 2.9–8.6ROR 5.0 · χ² 38 / p 4e-10 | 4.3 EB05 2.7 · IC025 +1.2 3/3 methods agree | Not in label — unassessed | serious PRR 10.0 | no trial data cached |
| Feeling abnormal | 89 | 5.0 4.1–6.1ROR 5.2 · χ² 281 / p 2e-63 | 4.8 EB05 4.1 · IC025 +1.9 3/3 methods agree | Not in label — unassessed | serious PRR 7.4 | no trial data cached |
| Mental disorder | 16 | 4.9 3.0–8.0ROR 5.0 · χ² 46 / p 5e-12 | 4.4 EB05 2.9 · IC025 +1.3 3/3 methods agree | Not in label — unassessed | serious PRR 5.3 | no trial data cached |
| Emotional disorder | 11 | 4.8 2.6–8.6ROR 4.8 · χ² 29 / p 4e-8 | 4.0 EB05 2.4 · IC025 +1.0 3/3 methods agree | Not in label — unassessed | serious PRR 7.2 | no trial data cached |
| Intentional product misuse | 29 | 4.5 3.1–6.4ROR 4.5 · χ² 75 / p 2e-18 | 4.2 EB05 3.1 · IC025 +1.5 3/3 methods agree | Reporting / coding artifact | serious PRR 5.3 · 89% consumer | no trial data cached |
| Convulsion (seizure) | 15 | 3.5 2.1–5.7ROR 3.5 · χ² 24 / p 5e-7 | 3.2 EB05 2.1 · IC025 +0.8 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 3.6 | no trial data cached |
| Suicide attempt | 15 | 3.3 2.0–5.5ROR 3.3 · χ² 22 / p 1e-6 | 3.1 EB05 2.0 · IC025 +0.8 | Labeled — boxed warning synonym match | serious PRR 3.3 | no trial data cached |
| Drug dependence | 33 | 2.7 1.9–3.8ROR 2.8 · χ² 35 / p 2e-9 | 2.6 EB05 2.0 · IC025 +0.8 | Reporting / coding artifact | serious PRR 2.7 · 85% consumer | no trial data cached |
| Product substitution issue | 11 | 2.6 1.4–4.6ROR 2.6 · χ² 9 / p 0.001 | 2.4 EB05 1.5 · IC025 +0.2 | Reporting / coding artifact | serious PRR 3.5 | no trial data cached |
Trial evidence (ClinicalTrials.gov)
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 |
|---|---|---|---|---|---|---|
| Depression | 187 | 11.0 9.6–12.6ROR 12.3 · χ² 1,705 / p <1e-300 | 10.9 EB05 9.6 · IC025 +3.2 3/3 methods agree | Labeled — boxed warning exact term | serious PRR 12.4 · 74% consumer | no trial data cached |
| Weight increased (weight gain) | 122 | 7.4 6.2–8.7ROR 7.9 · χ² 670 / p 6e-148 | 7.2 EB05 6.2 · IC025 +2.5 3/3 methods agree | Labeled (related wording) related wording | serious PRR 9.9 · 73% consumer | no trial data cached |
| Drug interaction | 100 | 8.5 7.0–10.2ROR 9.0 · χ² 655 / p 1e-144 | 8.2 EB05 6.9 · IC025 +2.7 3/3 methods agree | Reporting / coding artifact | serious PRR 7.9 | no trial data cached |
| Pharmaceutical product complaint | 97 | 49.6 40.9–60.2ROR 52.8 · χ² 4,558 / p <1e-300 | 49.0 EB05 41.3 · IC025 +5.0 3/3 methods agree | Not in label — unassessed | serious PRR 74.6 | no trial data cached |
| Feeling abnormal | 89 | 5.0 4.1–6.1ROR 5.2 · χ² 281 / p 2e-63 | 4.8 EB05 4.1 · IC025 +1.9 3/3 methods agree | Not in label — unassessed | serious PRR 7.4 | no trial data cached |
| Suicidal ideation (thoughts of suicide) | 51 | 7.5 5.7–9.8ROR 7.7 · χ² 280 / p 3e-63 | 7.1 EB05 5.6 · IC025 +2.3 3/3 methods agree | Labeled — boxed warning exact term | serious PRR 7.8 | no trial data cached |
| Drug withdrawal syndrome | 44 | 6.7 5.0–8.9ROR 6.8 · χ² 207 / p 4e-47 | 6.3 EB05 4.8 · IC025 +2.1 3/3 methods agree | Labeled (related wording) related wording | serious PRR 6.1 · 76% consumer | no trial data cached |
| Drug effect decreased | 43 | 10.6 7.9–14.2ROR 10.8 · χ² 363 / p 2e-81 | 10.1 EB05 7.7 · IC025 +2.7 3/3 methods agree | Reporting / coding artifact | serious PRR 22.1 · ♀ 40% (drug 61%) · 85% consumer | no trial data cached |
| Panic attack | 42 | 15.5 11.5–20.8ROR 15.9 · χ² 554 / p 8e-123 | 15.3 EB05 11.7 · IC025 +3.2 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 18.8 | no trial data cached |
| Serotonin syndrome | 36 | 25.3 18.3–34.9ROR 25.9 · χ² 815 / p 1e-179 | 25.0 EB05 18.8 · IC025 +3.7 3/3 methods agree | Labeled (related wording) related wording | serious PRR 25.6 · ♀ 83% (drug 61%) | no trial data cached |
| Withdrawal syndrome | 35 | 11.1 8.0–15.4ROR 11.4 · χ² 313 / p 2e-70 | 10.6 EB05 7.8 · IC025 +2.7 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 10.6 · 74% consumer | no trial data cached |
| Hypertensive crisis | 35 | 42.2 30.4–58.6ROR 43.1 · χ² 1,363 / p 1e-298 | 41.2 EB05 31.0 · IC025 +4.2 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 42.5 | no trial data cached |
| Drug dependence | 33 | 2.7 1.9–3.8ROR 2.8 · χ² 35 / p 2e-9 | 2.6 EB05 2.0 · IC025 +0.8 | Reporting / coding artifact | serious PRR 2.7 · 85% consumer | no trial data cached |
| Amnesia (memory loss) | 31 | 6.4 4.5–9.0ROR 6.5 · χ² 135 / p 1e-31 | 5.9 EB05 4.3 · IC025 +2.0 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 7.8 · 74% consumer | no trial data cached |
| Intentional product misuse | 29 | 4.5 3.1–6.4ROR 4.5 · χ² 75 / p 2e-18 | 4.2 EB05 3.1 · IC025 +1.5 3/3 methods agree | Reporting / coding artifact | serious PRR 5.3 · 89% 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.
- Pharmaceutical product complaint — n=97, PRR 49.6
- Orthostatic hypotension — n=22, PRR 16.9
- Crying — n=25, PRR 9.2
- Nervousness — n=25, PRR 6.4
- Feeling abnormal — n=89, PRR 5.0
✓ A hand-written Bradford Hill causality assessment exists for this drug: Phenelzine ↔ Serotonin syndrome.
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 Phenelzine?
In FDA FAERS, the most frequently co-reported reaction terms for Phenelzine are depression, weight increased, pharmaceutical product complaint, feeling abnormal, suicidal ideation, drug withdrawal syndrome. 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 Phenelzine have an FDA boxed warning?
Yes. The current FDA label carries a boxed warning: Suicidality and Antidepressant Drugs Antidepressants increased the risk compared to placebo of suicidal thinking and behavior (suicidality) in children, adolescents, and young adults in short-term studies of major depressive disorder (MDD) and other psychiatric disorders.
Do FAERS signals prove that Phenelzine 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 40483372-448f-4284-976c-8462ef256661, effective 20170929; matched on
openfda.generic_name.exact:"PHENELZINE SULFATE") - 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, 75 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.