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Also indexed as: Nardil
Phenelzine is a member of a group of drugs called monoamine oxidase (MAO) inhibitors (also called MAOIs). Phenelzine is sometimes used to treat people with depression who do not respond to other antidepressant drug therapy.
Summary of Interactions with Vitamins, Herbs, and Foods
In some cases, an herb or supplement may appear in more than one category, which may seem contradictory. For clarification, read the full article for details about the summarized interactions.
 May Be Beneficial: Depletion or interference—The medication may deplete or interfere with the absorption or function of the nutrient. Taking these nutrients may help replenish them. | Vitamin B6 |
 Avoid: Adverse interaction—Avoid these supplements when taking this medication because taking them together may cause undesirable or dangerous results. | Aspartame* Ephedra* Ginseng (species not specified)* Scotch broom St. John’s wort* Tyramine-containing foods |
| Side effect reduction/prevention | None known |
| Supportive interaction | None known |
| Reduced drug absorption/bioavailability | None known |
An asterisk (*) next to an item in the summary indicates that the interaction is supported only by weak, fragmentary, and/or contradictory scientific evidence.
Vitamin B6
Phenelzine has a chemical structure similar to other drugs (isoniazid and hydralazine) that can cause vitamin B6 deficiency. One case of phenelzine-induced vitamin B6 deficiency has been reported.1 Little is known about this interaction. People taking phenelzine should ask their doctor about monitoring vitamin B6 levels and considering supplementation.
Ephedra
Ephedra contains the chemical ephedrine, which may interact with phenelzine, causing potentially dangerous changes to blood pressure.2 People should read product labels for ephedra/ephedrine content. Ephedra and ephedrine-containing products should be avoided during phenelzine therapy. People with questions about phenelzine and ephedra/ephedrine should ask their doctor or pharmacist.
Ginseng (species not specified)
In a case report of a woman treated with phenelzine, addition of a ginseng-containing tea was associated with insomnia, headache, and tremor.3 Other contents of the tea were not reported. In a case report of a woman treated with phenelzine for depression, addition of ginseng (not further identified) was associated with hypomania (a mild form of mania), which the patient had not previously experienced.4 Until more is known, people should combine ginseng and phenelzine with caution after consulting a knowledgeable doctor.
St. John’s wort(Hypericum perforatum)
Although St. John’s wort contains chemicals that bind MAO in test tubes, it is believed that the action of St. John’s wort is not due to MAOI activity.5 However, because St. John’s wort may have serotonin reuptake inhibiting action (similar to the action of drugs such as Prozac®, it is best to avoid concomitant use of St. John’s wort with MAOI drugs.
Scotch broom (Cytisus scoparius)
Scotch broom contains high levels of tyramine. Combining phenelzine and Scotch broom may cause MAOI-type reactions (diarrhea, flushing, sweating, pounding chest, dangerous changes in blood pressure, and other symptoms).6 It is important for people taking phenelzine to avoid Scotch broom. People with questions about phenelzine and Scotch broom should ask their doctor.
Tyramine-containing foods
Phenelzine can alter metabolism of a chemical called tyramine that is present in certain foods, leading to diarrhea, flushing, sweating, pounding chest, dangerous changes in blood pressure, and other symptoms.7 It is important for people taking phenelzine to avoid tyramine-containing foods. People with questions about phenelzine and tyramine-containing foods should ask their doctor or pharmacist.
Aspartame
Two cases were reported involving men treated with phenelzine who experienced restlessness, agitation, tremor, and insomnia after drinking large quantities of cola beverages containing aspartame.8 Until more is known, people taking phenelzine should use aspartame-containing foods with caution.
1. Heller CA, Friedman PA. Pyridoxine deficiency and peripheral neuropathy associated with long-term phenelzine therapy. Am J Med 1983;75:887–8.
2. Threlkeld DS, ed. Central nervous system drugs, antidepressants, monoamine oxidase inhibitors. In Facts and Comparisons Drug Information. St. Louis, MO: Facts and Comparisons, Apr 1997, 264y.
3. Shader RI, Greenblatt DJ. Phenelzine and the dream machine-ramblings and reflections. J Clin Psychopharmacol 1985;5:65.
4. Jones BD, Runikis AM. Interaction of ginseng with phenelzine. J Clin Psychopharmacol 1987;7:201–2.
5. St. John’s wort, Hypericum perforatum. In American Herbal Pharmacopoeia and Therapeutic Compendium, ed. R Upton. Santa Cruz, CA: AHP, 1997.
6. Brinker F. Interactions of pharmaceutical and botanical medicines. J Naturopathic Med 1997;7(2):14–20.
7. Threlkeld DS, ed. Central Nervous System Drugs, Antidepressants, Monoamine Oxidase Inhibitors. In Facts and Comparisons Drug Information. St. Louis, MO: Facts and Comparisons, Apr 1997, 264y.
8. Shader RI, Greenblatt DJ. Phenelzine and the dream machine-ramblings and reflections. J Clin Psychopharmacol 1985:5:65.
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Learn more about the authors of Using Medicines with Vitamins and Herbs
The information presented in Healthnotes is for informational purposes only. It is based on scientific studies (human, animal, or in vitro), clinical experience, or traditional usage as cited in each article. The results reported may not necessarily occur in all individuals. For many of the conditions discussed, treatment with prescription or over the counter medication is also available. Consult your doctor, practitioner, and/or pharmacist for any health problem and before using any supplements or before making any changes in prescribed medications. Information expires September 2008.
