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Cannabis drug interactions

A prescription medical bottle containing cannabis flower

Article written by

April AcernoContent Writer

Content reviewed by

Dr. June ChinChief Medical Officer

Table of contents

  1. Common cannabis drug interactions
  2. Less common or severe cannabis drug interactions 
  3. Tips for safely using cannabis with other medications
  4. The takeaway: It helps to be aware of cannabis drug interactions
  5. Resources

Cannabis is relatively safe when taken by itself, causing minimal side effects in most users. But when combined with other substances, it can sometimes cause unwanted effects because of the way the drugs interact with each other.

Understanding the types of drugs that might interact with cannabis — also called marijuana or weed — can help you stay safe and ensure your medications are working effectively.

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Common cannabis drug interactions

Cannabis’s active compounds are called cannabinoids. These include cannabidiol (CBD) and tetrahydrocannabinol (THC). CBD and THC can sometimes prevent certain drugs from fully breaking down and leaving the body, which can increase side effects and, in severe cases, lead to overdose.

In other cases, cannabis may add to the immune-suppressing effects of medications or increase your risk of drowsiness.

Common marijuana drug interactions include:

  • Sedatives: Sedatives, including diazepam (Valium), zolpidem (Ambien), and eszopiclone (Lunesta), are commonly prescribed for insomnia and epilepsy. Cannabis may add to their drowsiness-causing effects. It may also prevent them from properly breaking down in the body.
  • Pain medications: Cannabis can interact with common pain medications, including opioids like morphine and oxycodone, and over-the-counter non-steroidal anti-inflammatory drugs (NSAIDs) like ibuprofen. Cannabis may interfere with how these drugs break down and leave your body.
  • Anticonvulsants (seizure medications): Using cannabis with anticonvulsant medications like valproic acid (Valproate) may lead to elevated levels of the drug in your body and, in rare cases, liver damage.
  • Alcohol: Combining cannabis with alcohol can increase side effects like dizziness, nausea, confusion, sedation, and impairment.

Cannabis interacts with over 400 drugs. How severe an interaction is depends on the drug itself, as well as your dosing and metabolism.

Less common or severe cannabis drug interactions 

Cannabis can interact with other compounds, including herbal supplements:

  • Melatonin: Both cannabis and melatonin can help with insomnia. But combining them might cause impairment, dizziness, nausea, and excessive drowsiness.
  • St. John’s Wort: St. John’s Wort is an herbal supplement used for depression. Combining it with cannabis may increase your risk of dizziness and impairment.
  • Valerian root: Valerian root is an herbal supplement used for anxiety and insomnia. Using it with cannabis may add to its sedative effects and cause confusion.
  • Echinacea: Cannabis and echinacea are broken down by the same enzymes in your liver. Consuming them together can cause elevated levels of both, increasing your risk of side effects.

Tips for safely using cannabis with other medications

If you’re planning to use cannabis alongside a medication or herbal supplement, talk with your doctor or a Leafwell telepharmacist to come up with a safe dosing plan.

Additionally, you can follow these general safety tips:

  • Start low and go slow: Opt for low doses of both cannabis and other medications and increase only as much as needed to achieve your desired effects over time. This decreases the risk of more severe side effects. Follow your doctor’s instructions if prescribed a specific medication regimen or dose.
  • Be mindful of timing: It might help to space out your medication and cannabis doses to minimize interactions. Consider how long it takes for a medication to begin working and plan accordingly. Cannabis can take effect in minutes and last for a couple of hours when inhaled, whereas edibles can take effect in 1 to 2 hours and last up to 8 hours.
  • Look out for a “grapefruit warning”: Grapefruit lowers levels of the same enzyme used to break down cannabis and many common medications. If your medication has a grapefruit warning on the label, it’s best to avoid consuming both grapefruit and cannabis when you take it.
  • Keep your medication list up to date: Be sure to inform any healthcare professional you see about all of the medications and supplements you’re taking, including cannabis.

Side effects to look out for 

On its own, cannabis may cause side effects, but these effects can become more severe when it’s combined with certain drugs.

Potential side effects include:

  • Dizziness
  • Drowsiness
  • Confusion
  • Dry mouth
  • Dry eyes
  • Increased appetite
  • Anxiety
  • Increased heart rate
  • Clamminess

If you’re experiencing any severe or unusual side effects, seek medical attention.

The takeaway: It helps to be aware of cannabis drug interactions

Although it’s often safe to use marijuana alongside your prescription medications, cannabis can interact with some drugs, supplements, and alcohol.

Before mixing any medication with cannabis, talk with your doctor or a Leafwell telepharmacist for personalized guidance.

Resources

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Frequently asked questions

What medications should you not smoke weed with?

Cannabis can negatively interact with hundreds of different medications, including some antidepressants, anti-anxiety medications, sedatives, and pain medications. With drug interactions, you might experience increased drowsiness, dizziness, or other side effects, depending on your medication. Weed can also cause it to take longer for your body to break down and use up your other medications.

Can you smoke weed while taking medication?

In many cases, it will be safe to smoke weed with your other medications. However, it depends on your medication and dosage, because cannabis can interact with some drugs. Be sure to speak with a healthcare professional to clarify if it’s advisable to smoke cannabis with your medication.

Does cannabis oil interfere with medications?

Cannabis oil can interfere with several medications, including anti-anxiety medications, anti-seizure medications, anticoagulants, pain medications, sedatives, and more.