Patient education: Monoamine oxidase inhibitor antidepressants (The Basics)

What are monoamine oxidase inhibitors? — 

Monoamine oxidase inhibitor antidepressants, or "MAOIs," include medicines used to treat severe depression, anxiety, and other psychiatric problems. MAOIs work by boosting the levels of certain chemicals in the brain that affect mood. Doctors might prescribe an MAOI if several other antidepressants have not worked.

MAOIs include phenelzine (brand name: Nardil), isocarboxazid (brand name: Marplan), and tranylcypromine (brand name: Parnate). These are taken as pills. Selegiline (brand name: Emsam) is another MAOI that comes as a skin patch you change once a day. There is also a pill form of selegiline, but it is used for treating Parkinson disease.

Are MAOIs safe? — 

It depends. MAOIs are an older type of antidepressant. They can be a good option for some people, but they aren't used much, because they can also be unsafe. They can interact badly with many other medicines, and you need to avoid certain foods while taking them.

Before prescribing an MAOI, your doctor will talk with you to make sure you can follow the special diet and avoid certain medicines. More information about this is below.

Who should not take MAOIs? — 

You should not take an MAOI if you:

●Cannot commit to following a special diet

●Need to take another medicine that can cause problems if taken along with an MAOI

●Have certain health conditions, such as seizures (epilepsy) or heart or liver disease

●Are pregnant, planning to get pregnant, or breastfeeding

●Take another kind of antidepressant, or stopped taking one in the last 2 to 6 weeks

●Need to have surgery or a procedure soon that requires anesthesia

●Have an adrenal gland problem called "pheochromocytoma"

Older people might not be able to take MAOIs. This is because the side effects can be worse.

MAOIs are not usually used in people who are at risk for suicide. This is because they are very dangerous if a person takes too much, or "overdoses." If you are having thoughts of hurting or killing yourself, tell your doctor or nurse immediately. Help is also available in the US and Canada from the 988 Suicide & Crisis Lifeline:

●To speak to someone, call or text 988.

●To talk to someone online, go to chat.988lifeline.org.

Can MAOIs cause side effects? — 

Yes. The most common side effects of MAOIs that come as pills include:

●Headache

●Trouble sleeping

●Feeling sleepy during the day

●Feeling very lightheaded when you first stand up

●Problems with sex

Less common side effects include:

●Dry mouth

●Upset stomach

●Constipation

●Weight gain

●Problems with urine flow

●Liver problems

●Muscle spasms

●Numbness, tingling, or burning feeling in the skin

●Low blood pressure

The selegiline skin patch has fewer side effects than MAOI pills. But the patch can cause headaches and trouble sleeping. Some people also have burning, itching, or a rash on their skin from the patch.

Other severe side effects can happen if you take an MAOI along with certain foods or other medicines. More information about this is below.

Can foods or other medicines change how MAOIs work? — 

Yes. These are called food or drug "interactions."

If your doctor prescribes an MAOI, you need to be careful about the foods you eat and other medicines you take:

●Food interactions – MAOIs block the body's ability to break down and get rid of "tyramine." This is a substance that is found naturally in some foods, and is also released when you digest protein. When there is too much tyramine in the body, it can cause dangerously high blood pressure and other serious problems. This can be a medical emergency.

While you are taking an MAOI antidepressant (and for a few weeks after you stop), you need to avoid foods and drinks that are high in tyramine. Foods high in tyramine include aged cheeses, cured meats, draft beer, and other fermented, overly ripe, or spoiled foods.

Your doctor or nurse will give you a complete list of foods and drinks to avoid or limit, and foods that are safe. The table has examples of foods to avoid and foods that are allowed on a low-tyramine diet (table 1).

If you use a selegiline patch at the lowest strength (6 mg per day), you usually do not need to follow a low-tyramine diet. But if your patch strength is 9 or 12 mg per day, you do need to follow the low-tyramine diet.

●Drug interactions – If you take an MAOI along with certain other medicines, this can cause dangerously high levels of a chemical called serotonin in the body. This is a serious, even fatal, emergency called "serotonin syndrome." It can cause restlessness, sweating, confusion, seizures, high fever, chest pain, sudden changes in blood pressure or heart rate, and passing out.

When taken along with an MAOI, some medicines can also cause dangerously high blood pressure. This is called "hypertensive crisis."

Some examples of medicines that can cause a dangerous interaction if taken with an MAOI include:

•Other antidepressants

•Opioid pain medicines

•Amphetamines ("stimulant" drugs used to treat ADHD)

•Cough and cold medicines that contain dextromethorphan

Before prescribing an MAOI, your doctor will review your other medicines. It's also important to tell them about anything else you take, such as herbs, supplements, or recreational drugs. Cocaine use can cause a very severe interaction with an MAOI. If you are prescribed any new medicines in the future, tell the doctor you take an MAOI.

Call for emergency help (in the US and Canada, call 9-1-1) if you get any severe symptoms, including:

●Flushing, sweating, vomiting

●Sudden, intense, or violent headache

●Confusion

●Passing out

●High fever

●Seizure

●Chest pain

●Fast or irregular heartbeat

●Overdose (you took too many pills)

When will I start to feel better? — 

Most antidepressants start to help within 2 weeks. But it usually takes at least 4 to 6 weeks before you feel the full effect. In some cases, it might take as long as 12 weeks.

If you don't feel any better after 2 to 4 weeks, ask your doctor or nurse what you can do. They might suggest 1 or more of these:

●Waiting to see if things change

●Taking a higher dose

●Trying a different medicine

●Adding or switching to another treatment

How long will I take the MAOI for? — 

MAOIs are typically prescribed for severe depression or depression that hasn't improved with other treatments. In this case, your doctor will most likely recommend taking the MAOI for at least a year. They will work with you to create a personalized treatment plan based on your symptoms.

People with depression who recover and then stop taking their medicine often get depressed again. The risk of this increases if you had several episodes of depression.

Do not stop taking your medicine without talking to your doctor. Stopping an antidepressant suddenly can cause symptoms such as headache, nausea, trouble sleeping, or dizziness. Your doctor will usually give you instructions on lowering the dose slowly to prevent these side effects.

If your doctor decides to switch you to a different antidepressant, you will need to wait at least 2 weeks after stopping the MAOI before starting the new medicine. During those 2 weeks, you will also need to keep avoiding foods high in tyramine and medicines that interact with MAOIs (see above).

How can I stay safe?

●Take your medicines exactly as instructed, so you get the correct amount of each. It might help to use reminders or a weekly pill box (picture 1).

●Wear a medical alert bracelet or carry a card that says you take an MAOI. This way, others will know you take the medicine if you have a medical emergency.

●If you have side effects like sleepiness or dizziness, do not drive or operate dangerous equipment. Alcohol can also make these side effects worse.

●Always check with your doctor before taking any new medicines, over-the-counter drugs, herbs, or supplements.

●Bring a list of the names and doses of all your medicines each time you visit any doctor. You can find an example of this kind of list at this website: www.fda.gov/media/73856/download.

For more detailed information about your medicines, ask your doctor or nurse for the patient drug information handout from UpToDate. It explains how to use each medicine, describes its possible side effects, and lists other medicines or foods that can affect how it works.

What if I want to get pregnant? — 

Depression can sometimes get worse during pregnancy and after birth. Antidepressants other than MAOIs might be used to treat severe depression during pregnancy. Talk with your doctor to understand the risks and benefits for your and your baby's health.

More on this topic

Patient education: Low-tyramine diet (The Basics)
Patient education: Commonly used medicines for depression (The Basics)
Patient education: Depression in adults (The Basics)
Patient education: When you have depression and another health problem (The Basics)
Patient education: Depression during and after pregnancy (The Basics)
Patient education: Serotonin syndrome (The Basics)
Patient education: Side effects from medicines (The Basics)
Patient education: Coping with high drug prices (The Basics)

Patient education: Depression treatment options for adults (Beyond the Basics)
Patient education: Depression in adults (Beyond the Basics)
Patient education: Coping with high prescription drug prices in the United States (Beyond the Basics)