Hydroxyzine is an antihistamine that can help treat anxiety, allergies, itchy skin, and some rashes. No recent research has identified potential interactions between hydroxyzine and cannabis, but this does not mean none exist.

The two may cause similar side effects, and using them together can intensify those side effects.

Hydroxyzine, which is available as Vistaril and Atarax, commonly causes dizziness and fatigue. Some people also experience these symptoms with cannabis. Using the two together can increase the risk of dizziness, falls, fainting, or accidents from exhaustion.

People who regularly use cannabis should tell a doctor before taking hydroxyzine. It is also important to discuss any other drugs because adding a third medication can increase the side effects of hydroxyzine and cannabis.

Read on to learn more about hydroxyzine and cannabis, including how they interact and potential risks.

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Hydroxyzine is the generic version of a drug sold as Atarax and Vistaril. It is an antihistamine. Antihistamines reduce the effects of histamine, a chemical the body releases in response to allergies and some irritants. They can also make a person sleepy and relaxed.

Hydroxyzine can treat the following conditions:

Doctors may also use it off-label for some other conditions, such as to manage symptoms of asthma.

Researchers have not studied it as a long-term anxiety treatment, so doctors may prescribe other medications for long-term use.

The medication label for hydroxyzine does not specifically list any issues around using it with cannabis, and there is no recent evidence suggesting that cannabis dangerously interacts with hydroxyzine.

Doctors have not established that either drug interferes with enzymes that metabolize the other drug. This means there is no evidence that cannabis weakens or intensifies the dosage of hydroxyzine, or vice versa.

This does not mean that there are no drug interactions. It simply means that no recent studies have found serious interactions.

Cannabis and hydroxyzine may still interact in several ways:

  • The two drugs can intensify the effects of one another. For example, cannabis may make a person feel sleepier than they otherwise would with hydroxyzine.
  • A person may develop unusual side effects with either or both drugs. For example, a person may find that cannabis and hydroxyzine do not make them nauseous separately, but that together they cause nausea.
  • The negative effects of either drug may be more noticeable when a person uses them together. Combining multiple drugs increases the risk of a drug overdose.
  • If a person takes another drug, the two drugs can change the effects of the third. For example, alcohol, hydroxyzine, and cannabis may negatively interact to cause a person to be sleepy or uncoordinated. The two drugs can also increase the risk of overdosing on certain other drugs.

The potential risks of hydroxyzine and cannabis are theoretical because no recent research has tested the two drugs together, and the medication label does not identify any specific interactions.

Some potential risks include:

  • Blood pressure and fainting: Cannabis can increase the risk of fainting by lowering blood pressure when a person stands. At high doses, hydroxyzine may also cause low blood pressure and potentially fainting. Using the two together may increase the risk, especially in someone who has low blood pressure.
  • Central nervous system depression: Drugs that slow down activity in the central nervous system may intensify the effects of cannabis, potentially causing slow breathing, trouble thinking clearly, or an overdose. It is possible that hydroxyzine may slow activity in the central nervous system, especially at high doses.
  • Dizziness: Some people experience dizziness with cannabis or with hydroxyzine. Using the two together may increase this effect. This can make driving or operating heavy machinery dangerous until a person understands how the drugs will affect them.

Another concern with hydroxyzine and cannabis is that taking additional drugs may cause extra side effects. A person can find that they have no serious side effects with cannabis and hydroxyzine, but that adding alcohol or any other drug that can induce sleepiness or dizziness intensifies the effects of both drugs.

A person should not take any other drugs when using hydroxyzine and cannabis. If a person begins taking a new prescription, it is important for them to tell a doctor about all drugs they take, including prescription and over-the-counter drugs, in addition to other substances, such as cannabis.

Using either drug during pregnancy may pose risks to the developing fetus, especially when a person uses them during the first trimester.

While researchers have not identified specific negative effects or risks of cannabis and hydroxyzine, these effects may still exist.

Taking multiple drugs together increases the risk of side effects and of overdosing. A person who uses either drug should talk with a doctor about the risks and benefits of drug use. There may also be strategies for reducing the risk, such as using the drugs at different times of the day or at lower doses.

Because cannabis is still illegal in 13 states in the United States, as of June 2022, some people are reluctant to tell a doctor about cannabis use.

It is important to find a provider who is knowledgeable about cannabis and willing to discuss harm-reduction strategies. People should be as transparent as possible with a doctor about the drugs they use, as not doing so may increase the risk of harmful side effects and even overdosing.