Can I take Sertraline and Fluoxetine together?

Why this happens

Both drugs are Selective Serotonin Reuptake Inhibitors (SSRIs) that have an additive effect on serotonin levels (pharmacodynamic interaction). Furthermore, fluoxetine interferes with the liver enzymes (specifically CYP2D6 and potentially others) responsible for clearing sertraline from your body, making sertraline levels rise higher than intended (pharmacokinetic interaction).

What you should do

You should not take these two medicines together unless specifically instructed and closely monitored by a specialist. If you are currently taking both, do not stop taking them abruptly, but contact your doctor immediately to discuss a safe plan. Seek urgent medical help if you experience agitation, hallucinations, a very fast heartbeat, or muscle twitching.

Important precautions

Depression and anxiety disorders

These medicines can increase thoughts of self-harm or suicide, particularly in the first few weeks of treatment or when the dose is changed. Patients under 25 are at higher risk. Seek medical help immediately if your mood worsens or you have distressing thoughts.

Serotonin Syndrome

Taking these medicines with other drugs that affect serotonin (such as St John’s Wort, tramadol, or triptans for migraine) can cause a life-threatening condition called serotonin syndrome. Symptoms include high fever, agitation, confusion, trembling, and sweating.

Bleeding disorders

These medicines can increase your risk of bleeding, especially in the stomach. This risk is much higher if you also take aspirin, ibuprofen (NSAIDs), or blood-thinning medicines like warfarin. Seek medical advice for unusual bruising or black, tarry stools.

Low blood sodium (Hyponatraemia)

These medicines can cause the level of sodium in your blood to fall too low, which can be serious. This is more common in elderly patients. Symptoms include extreme tiredness, confusion, muscle twitching, or fits.

Food and drink warnings

Alcohol

It is best to avoid or strictly limit alcohol while taking these medicines. Combining alcohol with antidepressants can increase drowsiness, dizziness, and coordination problems, and may make your depression or anxiety worse. There is also an increased risk of liver damage when mixing alcohol with certain medications.

Grapefruit juice

You should avoid drinking large amounts of grapefruit juice while taking sertraline. Grapefruit can increase the level of sertraline in your blood, which may increase the risk of side effects.

Caffeine (Coffee, tea, energy drinks)

Limit your intake of caffeine. These medicines can sometimes cause jitteriness, anxiety, or difficulty sleeping. Caffeine can make these side effects worse.

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.