Can I take Promethazine and Sertraline together?

Why this happens

Both drugs have a 'sedating' effect on the brain, which adds up when taken together. Additionally, both drugs can increase levels of a chemical called serotonin; if these levels get too high, it can cause serious side effects. There is also a small risk that both drugs together can interfere with the electrical signals in your heart (QT prolongation).

What you should do

Speak to your doctor or pharmacist before combining these medicines. If you do take them together, avoid driving or using machinery until you know how they affect you. Seek medical help immediately if you experience a very fast or irregular heartbeat, severe shivering, muscle stiffness, or extreme confusion.

Important precautions

Serotonin syndrome

Taking these medicines together increases the risk of serotonin syndrome, a rare but life-threatening reaction. Seek urgent care if you experience high fever, agitation, confusion, shivering, or severe muscle twitching.

Depression and anxiety disorders

You may experience an increase in suicidal thoughts or the urge to self-harm when first starting sertraline or changing the dose. This is more common in young adults under 25. Contact your doctor or go to hospital immediately if you notice any changes in your mood or behaviour.

Heart rhythm disorders (QT prolongation)

Both medicines can affect your heart rhythm, especially if you have existing heart disease. This can lead to a serious condition called QT prolongation. Contact your doctor immediately if you feel a racing heartbeat, palpitations, or dizziness.

Increased bleeding risk

Sertraline increases your risk of serious bleeding, especially in the stomach. This risk is much higher if you also take aspirin, ibuprofen (NSAIDs), or blood-thinning medicines like warfarin.

Breathing problems (e.g. asthma, COPD, sleep apnoea)

Promethazine can cause severe breathing difficulties and should be avoided if you have chronic lung disease or sleep apnoea.

Glaucoma (Closed-angle)

Promethazine can increase the pressure inside your eye. If you have closed-angle glaucoma, this medicine could cause a sudden, painful increase in eye pressure (acute glaucoma attack).

Driving and operating machinery

Promethazine causes significant drowsiness that can last into the next day. Do not drive or use tools if you feel sleepy or less alert.

Children under 2 years old

Promethazine must not be given to children under 2 years of age because it can cause fatal breathing difficulties (respiratory depression).

Food and drink warnings

Alcohol

It is best to avoid or strictly limit alcohol while taking these medicines. Combining alcohol with promethazine can cause extreme drowsiness and breathing difficulties. Combining alcohol with sertraline can increase the risk of side effects like dizziness and sleepiness. Both medicines, when mixed with alcohol, can significantly impair your coordination and judgement.

Grapefruit juice

Avoid drinking large amounts of grapefruit juice. Grapefruit can increase the level of sertraline in your blood, which may increase the risk of side effects.

Caffeine (Coffee, Tea, Energy Drinks)

Sertraline can sometimes make you feel restless or anxious. High amounts of caffeine can worsen these feelings or interfere with your sleep. Monitor your intake if you feel jittery.

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.