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Isocarboxazid Side Effects

In Summary

Commonly reported side effects of isocarboxazid include: dizziness and headache. Other side effects include: suicidal ideation, suicidal tendencies, drowsiness, sleep disorder, tremor, nausea, and orthostatic hypotension. See below for a comprehensive list of adverse effects.

For the Consumer

Applies to isocarboxazid: oral tablet

Along with its needed effects, isocarboxazid 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
  • Burning, crawling, itching, numbness, prickling, "pins and needles", or tingling feelings
  • chills
  • cold sweats
  • confusion
  • difficult urination
  • dizziness, faintness, or lightheadedness when getting up from lying or sitting position
  • fainting
  • fast, irregular, pounding, or racing heartbeat or pulse
  • fear or nervousness
  • heavy feeling
  • increased need to urinate
  • passing urine more often
  • restlessness
  • shakiness in the legs, arms, hands, or feet
  • sudden jerky movements of the body
  • sweating
  • trembling or shaking of the hands or feet
  • trouble sitting still
Incidence not known
  • Agitation
  • burning while urinating
  • change in consciousness
  • decrease in frequency of urination
  • decrease in urine volume
  • decreased urine output
  • depression
  • difficulty in passing urine (dribbling)
  • dizziness
  • false or unusual sense of well-being
  • headache
  • hostility
  • irritability
  • loss of bladder control
  • loss of consciousness
  • muscle twitching
  • nausea
  • need to keep moving
  • numbness or tingling of the hands, feet, or face
  • rapid weight gain
  • seeing, hearing, or feeling things that are not there
  • seizures
  • shakiness and unsteady walk
  • stupor
  • swelling of the face, ankles, or hands
  • unsteadiness, trembling, or other problems with muscle control or coordination
  • unusual tiredness or weakness

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
  • Decreased interest in sexual intercourse
  • drowsiness
  • inability to have or keep an erection
  • loss in sexual ability, desire, drive, or performance
  • relaxed and calm
  • sleepiness
  • sleeplessness
  • trouble sleeping
  • unable to sleep
  • unusual drowsiness, dullness, tiredness, weakness, or feeling of sluggishness
Incidence not known
  • Black tongue
  • blurred vision
  • change in vision
  • impaired vision
  • increased sensitivity of the skin to sunlight
  • itching
  • raised, dark red, wart-like spots on the skin, especially when used on the face
  • redness or other discoloration of the skin
  • severe sunburn
  • skin rash

For Healthcare Professionals

Applies to isocarboxazid: oral tablet


Common (1% to 10%): Orthostatic hypotension, palpitations
Frequency not reported: Disturbances in cardiac rhythm, peripheral edema[Ref]

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

Nervous system

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

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]


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]


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%): Anxiety, insomnia, sleep disturbance
Frequency not reported: Agitation, behavioral changes, confusion, suicidal behavior, suicidal ideation
Postmarketing reports: Euphoria, hallucinations[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]


1. "Product Information. Marplan (isocarboxazid)" Roche Laboratories, Nutley, NJ.

2. Cerner Multum, Inc. "UK Summary of Product Characteristics." O 0

Some side effects of isocarboxazid may not be reported. Always consult your doctor or healthcare specialist for medical advice. You may also report side effects to the FDA.

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