Can I take Lercanidipine and Promethazine together?

Why this happens

Lercanidipine works by relaxing your blood vessels to lower blood pressure. Promethazine, while primarily an antihistamine, can also cause blood vessels to widen slightly and has a sedating effect on the brain. When combined, these effects add together, increasing the risk of low blood pressure and sleepiness.

What you should do

You should use caution when taking these medicines together. Monitor your blood pressure regularly and be careful when getting out of bed or standing up. If you feel very dizzy or sleepy, avoid driving or operating machinery. If you experience fainting or severe dizziness, contact your doctor to see if your doses need adjusting.

Important precautions

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

Promethazine can cause severe breathing difficulties and should be avoided if you have serious lung disease or breathing problems, as it can suppress your respiratory system. Promethazine must not be given to children under 2 years of age because it can cause life-threatening breathing difficulties (respiratory depression).

Glaucoma or prostate issues

Promethazine can worsen symptoms of narrow-angle glaucoma (increasing eye pressure) or cause sudden inability to pass urine if you have an enlarged prostate.

Drowsiness and safety-critical tasks

Promethazine causes significant drowsiness that can last into the next day. Do not drive or operate machinery if you feel sleepy or if your alertness is impaired.

Severe liver or kidney disease

Lercanidipine is not recommended if you have severe liver or kidney problems. Ensure your doctor is aware of your condition before starting treatment.

Food and drink warnings

Alcohol

It is best to avoid or strictly limit alcohol while taking these medicines. For lercanidipine, alcohol can increase the blood-pressure-lowering effect, making you feel dizzy or faint. For promethazine, alcohol increases the sedative effect, making you dangerously drowsy and increasing the risk of breathing difficulties.

Grapefruit and grapefruit juice

You must not eat grapefruit or drink grapefruit juice while taking lercanidipine. Grapefruit can significantly increase the amount of the medicine in your blood, making side effects like dizziness, headaches, and a fast heartbeat much more likely.

High-fat meals

Lercanidipine should be taken at least 15 minutes before a meal. Taking it with or immediately after a high-fat meal can significantly increase the amount of medicine absorbed by your body, which may lead to more side effects.

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.