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Marplan Side Effects

Generic name: isocarboxazid

Medically reviewed by Last updated on May 22, 2023.

Note: This document contains side effect information about isocarboxazid. Some dosage forms listed on this page may not apply to the brand name Marplan.

Applies to isocarboxazid: oral tablet.


Oral route (Tablet)

Antidepressants increased the risk of suicidal thinking and behavior in children, adolescents, and young adults in short-term studies with major depressive disorder (MDD) and other psychiatric disorders. Short term studies did not show an increase in the risk of suicidality with antidepressants compared to placebo in adults beyond age 24, and there was a reduction in risk with antidepressants compared to placebo in adults aged 65 and older. This risk must be balanced with the clinical need. Monitor patients closely for clinical worsening, suicidality, or unusual changes in behavior. Families and caregivers should be advised of the need for close observation and communication with the prescriber. Not approved for use in pediatric patients.

Serious side effects of Marplan

Along with its needed effects, isocarboxazid (the active ingredient contained in Marplan) may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur while taking isocarboxazid:

Less common

Incidence not known

Other side effects of Marplan

Some side effects of isocarboxazid may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects.

Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

More common

Less common

Incidence not known

For Healthcare Professionals

Applies to isocarboxazid: oral tablet.


Orthostatic hypotension, disturbances in cardiac rhythm, and/or peripheral edema may be controlled by reducing the dose.[Ref]

Common (1% to 10%): Orthostatic hypotension, palpitations

Frequency not reported: Disturbances in cardiac rhythm, peripheral edema[Ref]

Nervous system

Very common (10% or more): Dizziness (up to 29%), headache (up to 15%)

Common (1% to 10%): Drowsy/drowsiness, forgetful, hyperactive, lethargy, myoclonic jerks, paresthesia, sedation, syncope, tremor

Frequency not reported: Hyperreflexia, mild headache, overactivity, peripheral neuritis

Postmarketing reports: Akathisia, ataxia, coma, neuritis[Ref]

Dizziness and/or drowsiness may be controlled by reducing the dose.[Ref]


Common (1% to 10%): Constipation, diarrhea, dry mouth, nausea

Frequency not reported: Vomiting

Postmarketing reports: Black tongue[Ref]

Constipation, dry mouth, nausea, and/or vomiting may be controlled by reducing the dose.[Ref]


Frequency not reported: Blurred vision

Postmarketing reports: Toxic amblyopia[Ref]

Blurred vision may be controlled by reducing the dose.

Toxic amblyopia was reported in a patient with schizophrenia who received this drug for approximately 1 year; however, no causal relationship to this drug was established.[Ref]


Frequency not reported: Muscle tremor[Ref]


Common (1% to 10%): Impotence, urinary frequency, urinary hesitancy

Frequency not reported: Difficulty in micturition, impairment of erection and ejaculation

Postmarketing reports: Dysuria, incontinence, sexual disturbances, urinary retention[Ref]


The most common adverse events were dizziness, headache, nausea, and dry mouth.[Ref]


Postmarketing reports: Impaired water secretion compatible with syndrome of inappropriate secretion of antidiuretic hormone (SIADH)[Ref]


Common (1% to 10%): Sweating

Frequency not reported: Skin rashes

Postmarketing reports: Photosensitivity, spider telangiectases[Ref]


Common (1% to 10%): Anxiety, insomnia, sleep disturbance

Frequency not reported: Agitation, behavioral changes, confusion, suicidal behavior, suicidal ideation

Postmarketing reports: Euphoria, hallucinations[Ref]

Insomnia may be controlled by reducing the dose.

Hallucinations have been reported with high doses, but have disappeared with dose reduction or discontinuation of therapy.[Ref]


Common (1% to 10%): Chills, heavy feeling

Frequency not reported: Fatigue, weakness[Ref]

Fatigue and/or weakness may be controlled by reducing the dose.[Ref]


Rare (less than 0.1%): Blood dyscrasias, granulocytopenia, purpura

Postmarketing reports: Hematologic changes[Ref]


Frequency not reported: Increased appetite, weight gain[Ref]

Frequently asked questions


1. Product Information. Marplan (isocarboxazid). Roche Laboratories. 2001;PROD.

2. Cerner Multum, Inc. UK Summary of Product Characteristics.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Some side effects may not be reported. You may report them to the FDA.