Can I take St John's wort and Fluoxetine together?

Why this happens

Both fluoxetine and St John's Wort work by increasing the levels of serotonin in the brain. When used together, they can raise these levels too high (a 'pharmacodynamic' interaction). Additionally, St John's Wort can change how the liver breaks down certain medicines, which can make the levels of fluoxetine in your blood unpredictable.

What you should do

Do NOT take St John's Wort if you are already taking fluoxetine (Prozac). If you are currently taking both, you should contact your GP or pharmacist immediately for advice before stopping either, as stopping antidepressants suddenly can also cause side effects. If you experience severe symptoms like confusion, high fever, or tremors, seek emergency medical help.

Important precautions

Serotonin Syndrome

Taking fluoxetine and St John's wort together significantly increases the risk of serotonin syndrome, a potentially life-threatening condition caused by excessive serotonin levels. Symptoms include high fever, agitation, confusion, and muscle twitching. Do not combine these treatments.

Depression and Mental Health

Like other antidepressants, St John's wort and fluoxetine may increase the risk of suicidal thoughts or self-harm, particularly when first starting treatment. Seek immediate medical help if your mood worsens.

Drug Interactions

St John's wort significantly reduces the effectiveness of many essential medicines, including the contraceptive pill, blood thinners (warfarin), epilepsy medications, and organ transplant drugs. Do not start it without a pharmacist checking your current medications.

Bleeding risk

Fluoxetine can increase your risk of bleeding, especially if you are also taking aspirin, NSAIDs (like ibuprofen), or blood-thinning medications (like warfarin). Seek medical advice if you notice unusual bruising or bleeding.

Photosensitivity

St John's wort can make your skin significantly more sensitive to sunlight, leading to severe sunburn or skin reactions even with limited exposure.

Food and drink warnings

Alcohol

It is best to avoid or strictly limit alcohol while taking these medicines. Combining alcohol with fluoxetine or St John's Wort can increase drowsiness and dizziness, and may worsen feelings of depression.

Caffeine (Coffee, Tea, Energy Drinks)

Fluoxetine can increase the effects of caffeine in your body. This may lead to feeling jittery, anxious, or having difficulty sleeping.

Foods high in Tyramine (e.g., aged cheeses, cured meats, soy sauce, marmite, overripe fruit)

While less common than with older prescription antidepressants, St John's Wort can potentially interact with tyramine-rich foods, leading to a sudden, dangerous increase in blood pressure (hypertensive crisis). You should consume these foods in moderation.

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.