Isocarboxazid
Isocarboxazid is an older antidepressant (an MAO inhibitor) used to treat depression, usually after other antidepressants have not worked well enough.
🧬 Where this information comes from Click to expand
The clinical label records used on this page are FDA-filed Structured Product Labeling (SPL) retrieved through openFDA. We identified 2 clinical label sets within the page’s selected clinical scope after exact ingredient or ingredient-combination matching and applicable route/form matching. Forms, routes, brands, labelers, strengths, and NDC product-record counts are built separately from matching FDA National Drug Code Directory records. The linked DailyMed document is a representative official source for verification, not the page’s only clinical source. View the linked label on DailyMed →
Isocarboxazid (Marplan) is an older MAO inhibitor antidepressant, on the U.S. market since about 1959. It blocks the enzyme monoamine oxidase to boost certain brain chemical messengers and is usually saved for depression that other antidepressants have not helped. Day to day, people most often notice dizziness or faintness on standing, dry mouth, nausea and drowsiness. The real danger is a hypertensive crisis, a sudden severe blood pressure spike set off by tyramine-rich foods or the wrong medicines, so a new pounding headache, racing heartbeat or stiff neck needs urgent care. It also carries a boxed warning about suicidal thoughts and behavior in people up to age 24.
Clinical pearls
- Check with your pharmacist before any new medicine, including cough syrups with dextromethorphan and decongestant cold, hay fever or diet products.
- Skip aged cheese, beer (even non-alcoholic), Chianti, soy sauce, sauerkraut, liver, pickled fish and overripe bananas or avocados.
- After fluoxetine, wait at least five weeks before starting Marplan; after stopping Marplan, wait about 10 days before another drug.
- Tell your dentist and every doctor you take Marplan, since meperidine, bupropion and buspirone are all off limits with it.
⚠️ FDA Boxed Warning — the FDA’s strongest safety alert ▾
Antidepressants, including Marplan, can increase suicidal thoughts and behavior in children, teens and young adults (up to age 24). In studies of children and adolescents, about 4% on antidepressants had these events versus 2% on placebo. No suicides occurred in those trials.
The risk did not rise in adults over 24, and it fell in adults 65 and older. Depression itself raises suicide risk. Marplan is not approved for children.
Everyone starting an antidepressant should be watched closely for worsening mood or unusual behavior changes, especially in the first few months and after dose changes. Families and caregivers should stay in close contact with the prescriber.
Patient information guide A plain-language walkthrough of Isocarboxazid, written from its FDA label.
What Isocarboxazid is used for
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Isocarboxazid is used to treat depression.
- Marplan tablets are indicated for depression, including major depressive disorder, often with anxiety symptoms.
- It is not a first-choice antidepressant for newly diagnosed depression.
- It is not approved for children or for bipolar depression.
How Isocarboxazid works
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Isocarboxazid is a non-selective MAO inhibitor. It blocks monoamine oxidase, an enzyme found in the brain, heart and liver. This is thought to raise brain levels of chemical messengers called biogenic amines.
Researchers do not fully know whether MAO inhibition itself or other actions explain the antidepressant effect.
Isocarboxazid dosage
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Marplan is taken by mouth as tablets, divided into two to four doses daily. Your prescriber starts low and increases slowly as you tolerate it. Many people do not feel the full benefit for 3 to 6 weeks, and the label says continued use is unlikely to help if there is no response by then.
- After your best response, the dose may be slowly lowered over several weeks.
- Follow your prescriber and label directions exactly.
Dosing details from the FDA-approved label
From the Isocarboxazid prescribing information (“Dosage and Administration”). Doses are set by your prescriber for your product, condition, kidney function and age — never change a dose on your own.
- Dosage for Marplan (no specific condition named; individually adjusted)
- Start with one tablet (10 mg) twice daily
- If tolerated, may be increased by increments of one tablet (10 mg) every 2 to 4 days to achieve four tablets daily (40 mg) by the end of the first week of treatment
- Then may be increased by increments of up to 20 mg/week, if needed and tolerated
- Daily dosage should be divided into two to four dosages
- After maximu
- Maximum: 60 mg/day
- Caution is indicated when a dose of 40 mg/day is exceeded because of limited experience at the higher end of the dose range; beneficial effect may not be seen for 3 to 6 weeks.
Read the label’s full dosing text
DOSAGE AND ADMINISTRATION For maximum therapeutic effect, the dosage of Marplan must be individually adjusted on the basis of careful observation of the patient. Dosage should be started with one tablet (10 mg) of Marplan twice daily. If tolerated, dosage may be increased by increments of one tablet (10 mg) every 2 to 4 days to achieve a dosage of four tablets daily (40 mg) by the end of the first week of treatment. Dosage can then be increased by increments of up to 20 mg/week, if needed and tolerated, to a maximum recommended dosage of 60 mg/day. Daily dosage should be divided into two to four dosages. After maximum clinical response is achieved, an attempt should be made to reduce the dosage slowly over a period of several weeks without jeopardizing the therapeutic response. Beneficial effect may not be seen in some patients for 3 to 6 weeks. If no response is obtained by then, continued administration is unlikely to help. Because of the limited experience with systematically monitored patients receiving Marplan at the higher end of the currently recommended dose range of up to 60 mg/day, caution is indicated in patients for whom a dose of 40 mg/day is exceeded (see ADVERSE REACTIONS ).
Read the full Dosage and Administration section on DailyMed →
Isocarboxazid side effects
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The most common side effects in studies were:
Common side effects
- Nausea
- Dry mouth
- Dizziness
- Low blood pressure and faintness
- Drowsiness
When to get medical help
- Call your doctor right away if you have a new or frequent headache, a pounding or racing heartbeat, or a sense of tightness in the throat or chest. These can be early signs of a dangerous blood pressure spike (hypertensive crisis).
- Other warning signs of a blood pressure spike include a stiff or sore neck, nausea or vomiting, heavy sweating, and sensitivity to light. Get emergency help if you have them.
- Call your prescriber right away if depression worsens, or if you notice suicidal thoughts, agitation, panic, irritability, aggression, restlessness or unusual changes in behavior.
- Tell your doctor if you feel faint or too drowsy to drive or use machinery.
Call your doctor right away for severe or frequent headache, palpitations, chest or throat tightness, neck stiffness, or heavy sweating, since these may signal a blood pressure crisis.
Isocarboxazid warnings and precautions
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- Hypertensive crisis: a dangerous blood pressure spike, sometimes fatal, linked to certain foods and drugs. Bleeding in the brain has been reported.
- Suicide risk: boxed warning for people up to age 24. Watch for worsening mood and unusual behavior.
- Bipolar disorder: antidepressants alone may trigger mania in people at risk, so screening is needed.
- Second-line use: reserved for people who have not responded to other antidepressants.
- Higher doses: limited experience above 40 mg per day, so caution is advised.
- Drowsiness and faintness may affect driving or machinery use.
Isocarboxazid interactions
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Marplan interacts with many drugs and foods, mostly because of blood pressure and serotonin-related reactions.
- Other MAO inhibitors and tricyclic-type antidepressants: dangerous combinations, including seizures and coma.
- SSRIs, such as fluoxetine, sertraline and paroxetine: serious, sometimes fatal reactions; waiting periods apply.
- Bupropion, buspirone, dextromethorphan, meperidine: should not be combined.
- Amphetamines and decongestant cold or diet products: can cause blood pressure spikes.
- High-tyramine foods like aged cheese, tap or non-alcoholic beer, Chianti, soy sauce and sauerkraut: risk of hypertensive crisis.
- Alcohol and excess caffeine: avoid.
- Disulfiram: use with caution.
Interactions listed in the FDA-approved label
From the Isocarboxazid prescribing information (“Drug Interactions”): what the manufacturer studied or reported to the FDA.
- Antabuse (disulfiram): In a single study, rats given high intraperitoneal doses of an MAO inhibitor plus disulfiram experienced severe toxicity, including convulsions and death. Marplan should be administered with caution to patients receiving Antabuse.
- Other psychotropic agents: Possible potentiating effects, especially in patients who may subject themselves to an overdosage of drugs. Concomitant use is generally not recommended; if combination therapy is needed, give careful consideration to the pharmacology of all agents to be used.
- Other drugs prescribed after discontinuing Marplan: The monoamine oxidase inhibitory effects of Marplan may persist for a substantial period after discontinuation of the drug. To avoid potentiation, allow an interval of 10 days when terminating Marplan and beginning therapy with another agent.
Read the label’s full interactions text
Drug Interactions See CONTRAINDICATIONS , WARNINGS , and PRECAUTIONS sections for information on drug interactions. Marplan should be administered with caution to patients receiving Antabuse ® (disulfiram, Wyeth-Ayerst Laboratories). In a single study, rats given high intraperitoneal doses of an MAO inhibitor plus disulfiram experienced severe toxicity, including convulsions and death. Concomitant use of Marplan and other psychotropic agents is generally not recommended because of possible potentiating effects. This is especially true in patients who may subject themselves to an overdosage of drugs. If combination therapy is needed, careful consideration should be given to the pharmacology of all agents to be used. The monoamine oxidase inhibitory effects of Marplan may persist for a substantial period after discontinuation of the drug, and this should be borne in mind when another drug is prescribed following Marplan. To avoid potentiation, the physician wishing to terminate treatment with Marplan and begin therapy with another agent should allow for an interval of 10 days.
Not a complete list. The label covers the interactions the manufacturer studied or reported, and our own interaction database does not cover every medicine either. Bring your full medication list, including vitamins and herbal products, to your pharmacist.
Before taking Isocarboxazid
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- Do not use if allergic to isocarboxazid.
- Avoid with heart or blood vessel disease, high blood pressure, brain blood vessel problems, or a history of headache.
- Avoid with pheochromocytoma, liver disease history or abnormal liver tests, or severe kidney impairment.
- Not approved for children.
- Tell your doctors and dentist you take it.
Isocarboxazid overdose
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Overdose can cause fast heartbeat, low blood pressure, coma, seizures, slowed breathing, fever and sweating. These signs may last 8 to 14 days. Contact a poison control center or seek emergency care right away.
What Isocarboxazid does in the body
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Isocarboxazid inhibits MAO in the brain, heart and liver. This is thought to increase brain levels of certain chemical messengers. Because MAO is found throughout the body, the drug has a number of effects, including on blood pressure.
How to store Isocarboxazid
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Store at 77ºF (25ºC); excursions permitted to 59º to 86ºF (15º to 30ºC) . Dispense in a tight, light-resistant container as defined in USP.
Written from the FDA-approved label with AI and reviewed by our pharmacy team. How we use AI →
Supplements & herbs that interact with Isocarboxazid
81 supplements and herbal products have documented interactions with Isocarboxazid in the licensed clinical database we use. Most are manageable — but your pharmacist should know about everything you take, including vitamins and herbals.
- Major · 14
- Moderate · 55
- Minor · 12
Educational information from a licensed clinical database (Natural Medicines) — see our data sources & update cadence. Not medical advice: an interaction being documented does not mean it will happen to you; do not start or stop medications or supplements without professional guidance.
Nutrient depletion considerations
Isocarboxazid has been associated with lower levels of 1 nutrient in the clinical literature. This does not mean a deficiency will occur — it means these may be worth discussing with your pharmacist or healthcare provider, especially with long-term use.
Educational information from a licensed clinical database (Natural Medicines) — not medical advice. Do not start or stop medications or supplements without professional guidance.
Isocarboxazid: pharmacist answers to common questions
Quick, plain-English answers to the questions patients ask most about Isocarboxazid — the kind of thing our pharmacy team would talk through with you at the counter.
What is Marplan used for?
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How should I take it, and how long until it works?
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Are there foods I need to avoid?
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Can I take cold medicine or other drugs with it?
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What side effects are common?
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When should I call my doctor right away?
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Is Isocarboxazid available over the counter?
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When was Isocarboxazid first available?
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Answers drafted from the FDA-approved label with AI and reviewed by our pharmacy team. How we use AI →
More about Isocarboxazid on HelloPharmacist
Isocarboxazid forms and strengths (how it comes)
Isocarboxazid is available in 1 form. Different forms and brands can have different approved uses, doses, schedules, and directions. Follow the instructions for your exact product, and do not switch forms without guidance from your prescriber or pharmacist.
Tablet
How this form is used
- Marplan is used to treat depression.
- Marplan is generally not a first-choice antidepressant for newly diagnosed depression.
- Marplan is taken by mouth, with the daily amount divided into two to four doses.
- Marplan dosing is adjusted gradually based on response and tolerance.
- Marplan may take 3 to 6 weeks to show benefit.
Isocarboxazid on the U.S. market: products, makers and brands
How Isocarboxazid appears in the FDA’s National Drug Code Directory — including its dosage forms, strengths, brand names, manufacturers, and FDA-listed product records. These are directory records, not sales or prescription volume.
1 company lists 1 Isocarboxazid product record with the FDA, mostly as tablet; the earliest marketing or approval year on record is 1959. Brand names on the directory include Marplan; the rest are generics.
Also listed with the FDA, not a patient dose form: Powder (1) — bulk drug substance sold to compounders/manufacturers and multi-item kits. These aren’t counted in the dose-form total above.
Compare Isocarboxazid products
A representative set of FDA-listed product records for Isocarboxazid — across manufacturers, strengths, and dosage forms, grouped by form with each product’s manufacturer and how the FDA approved it. The same medicine may be made and packaged by different companies, so a single drug can have many directory entries. (It’s also why a refill can look different — a new shape, color, or box — even though it contains the same medication.)
| Strength | Route | Manufacturer / Labeler | Category ⓘ | Details |
|---|---|---|---|---|
| 💊Tablet | ||||
| 10 mg | Oral | Lifsa Drugs LLC | NDA | View NDC → |
Showing 1 of 1 products — FDA National Drug Code Directory. See every product, package size and price: browse all 1 Isocarboxazid NDCs →
Isocarboxazid side effects reported to the FDA (FAERS)
After a medicine reaches the market, patients, doctors and drugmakers can send the FDA reports of problems they think may be linked to it. Here’s what’s been reported for Isocarboxazid — a signal of what to watch for, not proof the drug caused it.
Source: openFDA, from the FDA Adverse Event Reporting System (FAERS). These are voluntary reports — they don’t prove the drug caused the effect, and counts reflect how often something was reported, not how often it actually happens. Reports also often name the very problem the medicine is taken for — a common reason to file one is that the drug didn’t help — so for a pain reliever you may see “pain” high on the list; that points to why the report was filed, not to the drug causing the symptom. This counts every report that lists Isocarboxazid in any role, so the total runs higher than the FDA’s official dashboard, which counts only cases where the drug is the suspect. For the authoritative figures, see the FDA FAERS Public Dashboard. Always talk to your pharmacist or doctor.
Isocarboxazid FDA approval history
How Isocarboxazid went from FDA review to the pharmacy shelf — the key milestones in its regulatory journey.
Source: Drugs@FDA.
Isocarboxazid recall history
A recall is when a specific batch of a medicine is pulled from the market — usually a manufacturing issue, not a problem with the drug itself. Class I is most serious, Class III least.
The FDA’s enforcement reports list no Isocarboxazid recalls since July 2021.
✅No Isocarboxazid recalls on record since July 2021Source: FDA enforcement (recall) reports, via openFDA; our copy was last updated Sep 24, 2026.
RxNorm Concept Web — From Ingredient to Every Form and Strength
This page starts with one ingredient concept (IN). The branches below show its dose-form concepts (SCDF), then the available clinical drug and strength concepts (SCD). Combination products remain separate concepts with their own pages.
RxCUI 6011 1 dose form · 1 strength
-
Dose form (SCDF) Oral Tablet RxCUI 370712In current FDA listingsClinical drug / strength (SCD) 10 MGRxCUI 104837
Look up RxCUI 6011 in the RxCUI Atlas →
RxNorm is the U.S. National Library of Medicine’s normalized drug vocabulary. Its concept hierarchy can include forms that are not currently marketed; the status on each branch compares that concept with current FDA listings. RxCUIs identify vocabulary concepts, not individual packages or manufacturers.
Isocarboxazid supply and shortage status
Whether Isocarboxazid is in short supply in the U.S. right now, plus any shortage history the FDA has on record. A shortage usually reflects a manufacturing or demand issue — not a safety problem with the drug.
Source: openFDA, from the FDA Drug Shortages database.
Isocarboxazid brand names
Isocarboxazid is sold under one brand name in the FDA directory — Marplan. A brand and its generic contain the same active ingredient; the brand name belongs to one company's product.
Who makes Isocarboxazid: manufacturers and labelers
One company lists Isocarboxazid products with the FDA. By number of product records, the largest are Lifsa Drugs LLC. Labelers include manufacturers and repackagers; the product in your bottle depends on which one your pharmacy stocks.
Isocarboxazid drug class (RxNorm)
Isocarboxazid belongs to the Monoamine Oxidase Inhibitor class.
Classified by RxNorm RxClass — the U.S. National Library of Medicine's standardized drug-classification service (Established Pharmacologic Class from the FDA, the ATC drug family from the WHO, and mechanism of action). Reference only, not medical advice.
Sources for this Isocarboxazid page
Core label, product, RxNorm, safety, and utilization data on this page come from the sources identified below. AI-written, editorial, and licensed sections are labeled separately.
How this page is built
HelloPharmacist combines public FDA and NLM records and does not author the underlying clinical facts. The plain-language sections are written with AI from the FDA-approved label text and reviewed by our pharmacy team before publication. Lifsa Drugs LLC is the representative DailyMed label linked for verification and dates. This is general education, not medical advice: always talk to your doctor or pharmacist about your own medicines. How we build and review drug pages →