Marijuana and Prescribed Medications

This information was prepared by the National Cannabis Prevention and Information Centre in Australia, and used with permission.  Some information may not be accurate for U.S. readers.

Sometimes people use marijuana (and other drugs) in the belief that it will help them cope better with their problems and feelings. Using marijuana in this way, however, can cause those problems to become more severe and difficult to manage in the long-term.

The Effects of Marijuana on Mental Health

Marijuana use can have a range of mental health effects on people. Although rare, sometimes it can produce anxiety and panic in a person after a single use. In high doses, marijuana can cause confusion, thought disorder and hallucinations.

Some people are more vulnerable than others to experiencing these negative effects of marijuana, especially those with a personal or family history of mental illness. People who start using marijuana young, or use marijuana heavily, are more likely to experience psychotic disorders and depression later in life.

Doctors prescribe medication for depression, psychosis, bipolar affective disorder or schizophrenia to bring relief from the unpleasant symptoms that a patient may be experiencing. If that person continues to use marijuana while taking prescribed medications, unknown reactions can occur, which may make their condition worse. It also makes it very difficult for their doctor to prescribe the right drug at the right dose to improve their symptoms, as well as increasing the risk of non- compliance with medication regimes.

Mixing Marijuana with Antidepressant Medication

People who have been diagnosed with depression can be prescribed antidepressants. There are four main groups of antidepressants:

Very little research has been conducted on the effects of using marijuana while taking prescribed antidepressant medication. The side-effects of antidepressants can be similar to those produced by marijuana use however, and these include the following:

The danger of using marijuana while on antidepressants is that it can intensify any or all of these side effects and make a person feel worse.

Mixing Marijuana with Antipsychotic Medication

Antipsychotic medication is prescribed for people who have had psychotic episodes and have been diagnosed with schizophrenia. Common antipsychotic medications used in Australia are:

Antipsychotic medications are most effective in treating the hallucinations and delusions associated with schizophrenia and other psychotic disorders, however they may not help with other symptoms such as motivation and emotional responsiveness. Because of this, people with schizophrenia can experience depression which may also need to be treated. All these symptoms are made worse if marijuana is being used.

Research suggests that counselling can greatly improve the chances of a person giving up or cutting down their marijuana use while taking medication.

While there is very little research on the effects of the combination of marijuana and antipsychotic medications, there is evidence that suggests that those people prescribed Clozopine experience less craving for marijuana than those who are prescribed Resperidone or Quetiapine. Further research into this area is being conducted.

Getting Help

If you use marijuana regularly and take prescribed medications, or know someone who does, the following things may help:

Remember, the medications are prescribed to make people feel better. Using marijuana as well, will make the symptoms worse and the medications less effective.

This information adapted with permission from the National Cannabis Prevention and Information Centre in Australia.