MAO-B inhibitors

MAO-B inhibitors are used to treat the symptoms of Parkinson's. They prevent the breakdown of the chemical messenger dopamine in the brain.

How do MAO–B inhibitors work?

Dopamine is a chemical messenger made in the brain. The symptoms of Parkinson’s appear when your dopamine levels become too low. This is because many of the cells in your brain that produce dopamine have died or are dying.

Unfortunately, taking dopamine as a drug treatment for Parkinson’s doesn't help because it can’t cross into your brain where it’s needed.

MAO–B inhibitors can help your nerve cells make better use of the dopamine that they do have.

They do this by blocking an enzyme called monoamine oxidase type B (MAO–B), which breaks down dopamine in your brain. This helps to increase the amount of dopamine that the brain can use, which helps to relieve the symptoms of Parkinson’s.

When are MAO–B inhibitors used?

An MAO–B inhibitor can be used on its own in early Parkinson’s, or in combination with other drugs at all stages of Parkinson’s.

These drugs are mainly available as tablets.

What types of MAO–B inhibitors are there?


  • Azilect (tablets)


  • Unbranded (tablets)
  • Eldepryl (tablets)
  • Zelapar (tablets that dissolve on the tongue)

Benefits of MAO–B inhibitors

Improving Parkinson’s symptoms

On its own, an MAO–B inhibitor can help with some Parkinson’s symptoms, but the effects are modest and it may become less effective over time.

You don't have to wait to get the maximum dose

Many drug treatments for Parkinson’s have to be started gradually, with the dose slowly being increased over time. This is not the case for MAO-B inhibitors.

Delaying levodopa treatment

By taking an MAO–B inhibitor at an early stage of Parkinson’s, you may be able to delay taking levodopa until your symptoms become more difficult to manage.

Helping levodopa work better

When you have been taking levodopa for a while, you may find that its effects wear off too quickly. An MAO–B inhibitor can help with this.

Taking an MAO–B inhibitor may also reduce the dose of levodopa you need and lengthen the time between your doses of levodopa.

Risks and side effects of MAO–B inhibitors

Combination with antidepressants

If you’re taking some types of antidepressant, you might not be able to take MAO–B inhibitors, as these drugs can interact with each other to raise blood pressure to a dangerous level.

If you are taking antidepressants, your specialist should be able to advise you on how to take these alongside your Parkinson’s medication.

Combination with decongestants

Decongestants or cold remedies can affect some types of MAO–B inhibitors. If you need to use one of these products, check with your pharmacist to find out which one is safest to use.

Worse levodopa side effects

Because MAO–B inhibitors strengthen levodopa, the side effects of levodopa, including involuntary movements and sickness, may get worse too.

If this happens, your specialist or Parkinson’s nurse can reduce your dose of levodopa.

other side effects

The patient information leaflet that comes with your medication will tell you the full range of side effects that you may experience.

Some of the possible side effects include:

  • headaches
  • aching joints
  • indigestion
  • flu-like symptoms
  • depression

Find out more about the side effects of Parkinson's drugs.

Last updated August 2015. We review all our information within 3 years. If you'd like to find out more about how we put our information together, including references and the sources of evidence we use, please contact us at [email protected].