Monoamine oxidase inhibitors (MAOIs)
Monoamine oxidase inhibitors (MAOIs)
Monoamine oxidase inhibitors (MAOIs) were the first type of antidepressant developed. They're effective, but they've generally been replaced by antidepressants that are safer and cause fewer side effects.
Use of MAOIs typically requires diet restrictions because they can cause dangerously high blood pressure when taken with certain foods or medications. In spite of side effects, these medications are still a good option for some people. In certain cases, they relieve depression when other treatments have failed.
How MAOIs work
Antidepressants such as MAOIs ease depression by affecting chemical messengers (neurotransmitters) used to communicate between brain cells. Like most antidepressants, MAOIs work by changing the levels of one or more of these naturally occurring brain chemicals.
An enzyme called monoamine oxidase is involved in removing the neurotransmitters norepinephrine, serotonin and dopamine from the brain. MAOIs prevent this from happening, which makes more of these brain chemicals available. This is thought to boost mood by improving brain cell communication.
MAOIs also affect other neurotransmitters in the brain and digestive system, causing side effects. MAOIs are sometimes used to treat conditions other than depression, such as Parkinson's disease.
MAOIs approved to treat depression
The Food and Drug Administration (FDA) has approved these MOAIs to treat depression:
Selegiline is available as a skin (transdermal) patch. Using a patch may cause fewer side effects than MAOIs taken by mouth. If you're using the lowest dose patch, you may not need diet restrictions, but ask your doctor.
Side effects of MAOIs
Because of side effects and safety concerns, MAOIs are most often tried when other antidepressants don't work.
The most common side effects of MAOIs include:
Other possible side effects include:
Safety concerns with MAOIs
Consider these issues and discuss them with your doctor before taking an MAOI:
Suicide risk and antidepressants
Most antidepressants are generally safe, but the FDA requires that all antidepressants carry black box warnings, the strictest warnings for prescriptions. In some cases, children, teenagers and young adults under 25 may have an increase in suicidal thoughts or behavior when taking antidepressants, especially in the first few weeks after starting or when the dose is changed.
MAOIs are generally not prescribed for children, but anyone taking an antidepressant should be watched closely for worsening depression or unusual behavior. If you or someone you know has suicidal thoughts when taking an antidepressant, immediately contact your doctor or get emergency help.
Keep in mind that antidepressants are more likely to reduce suicide risk in the long run by improving mood.
Stopping treatment with MAOIs
Talk to your doctor before you stop taking an MAOI. Stopping treatment with MAOIs has been associated with flu-like symptoms, including nausea, vomiting and feeling generally unwell (malaise).
If you stop an MAOI suddenly, you're more likely to experience a withdrawal-type reaction. Rarely, discontinuation syndrome can occur, which causes uncommon withdrawal symptoms such as insomnia, confusion, detachment from reality (psychosis), agitation and convulsions. You may need to wait two or more weeks between the use of MAOIs and other antidepressants to avoid serotonin syndrome.
Work with your doctor to gradually and safely decrease your dose.
Finding the right antidepressant
Each person reacts differently to a particular antidepressant and may be more likely to have certain side effects. Because of this, one antidepressant may work better for you than another. When choosing an antidepressant, your doctor will take into account your symptoms, what health problems you have, what other medications you take and what has worked for you in the past.
Inherited traits play a role in how antidepressants affect you. In some cases, where available, results of special blood tests may offer clues about how your body may respond to a particular antidepressant. The study of how genes affect a person's response to drugs is called pharmacogenomics. However, other variables besides genetics can affect your response to medication.
Typically, it takes several weeks or longer before an antidepressant is fully effective and for initial side effects to ease up. You may need to try several antidepressants before you find the right one, but hang in there. With patience, you and your doctor can find a medication that works well for you.
Last Updated: 2013-06-21
© 1998-2014 Mayo Foundation for Medical Education and Research (MFMER). All rights reserved. A single copy of these materials may be reprinted for noncommercial personal use only. "Mayo," "Mayo Clinic," "MayoClinic.com," "Mayo Clinic Health Information," "Reliable information for a healthier life" and the triple-shield Mayo logo are trademarks of Mayo Foundation for Medical Education and Research.
Terms and conditions of use