Can I take CBD oil and Clozapine together?

Why this happens

Clozapine is broken down in the liver by specific proteins (enzymes) called CYP1A2 and CYP3A4. CBD oil blocks these proteins from working properly, which stops the body from clearing clozapine. This causes the medication to build up to potentially toxic levels. Both drugs also have calming effects on the brain that add together.

What you should do

You must speak to your doctor or psychiatrist before taking CBD oil if you are prescribed clozapine. Do not start, stop, or change your dose of CBD without medical supervision. Your doctor may need to monitor your blood levels more frequently or adjust your clozapine dose to ensure it remains at a safe level. If you feel unusually tired, dizzy, or develop a fever, contact your healthcare provider immediately.

Important precautions

Clozapine toxicity

CBD oil can significantly increase the levels of clozapine in your blood, raising the risk of serious side effects like seizures or heart problems. Do not start CBD without specialist supervision.

Agranulocytosis (low white blood cells) - clozapine

You must have regular blood tests. If you develop a fever, sore throat, or any flu-like symptoms, you must contact your doctor immediately as this can be life-threatening.

Constipation

Clozapine can cause severe constipation that may lead to bowel obstruction. You must tell your doctor if you are not opening your bowels regularly.

Smoking habits

If you start or stop smoking, or change to vaping, you must tell your doctor. Changes in nicotine intake can significantly change the level of clozapine in your blood, which may require a dose adjustment.

Food and drink warnings

Alcohol

Alcohol can increase the sedative effects of clozapine, making you feel very drowsy and increasing the risk of falls or accidents. It may also increase the risk of side effects like dizziness and blurred vision.

Caffeine (Coffee, Tea, Cola, Energy drinks)

Caffeine can significantly increase the levels of clozapine in your blood, which may lead to more side effects. Conversely, if you suddenly stop drinking caffeine, your clozapine levels could drop, making the medicine less effective. Try to keep your caffeine intake consistent. CBD may also interfere with how your body breaks down caffeine, potentially making you feel more jittery.

Grapefruit juice

Grapefruit and grapefruit juice can interfere with the enzymes that break down CBD in your body. This can lead to higher levels of CBD in your bloodstream, potentially increasing the risk of side effects.

High-fat meals

Taking CBD oil with a high-fat meal can significantly increase the amount of CBD absorbed into your body (sometimes by 3 to 4 times). To keep your levels stable, you should be consistent: either always take it with food or always take it on an empty stomach.

Using other medicines

Taking multiple medicines? Our Medicines Interaction Checker helps you check whether your prescriptions, over-the-counter medicines, and supplements are safe to take together. Simply search for your medicines to see potential interactions and what to do about them.

Disclaimer

This information is for general educational purposes only and should not be relied upon as a substitute for professional medical advice. Always consult your GP, pharmacist, or another qualified healthcare professional before making decisions about your medications. Individual circumstances may vary, and only a healthcare professional who knows your medical history can provide personalised guidance.