Can I take Lercanidipine and Promethazine together?
Drug interaction guide
Originally published 25 Jan 2026
Meets Patient’s editorial guidelines
- DownloadDownload
- Share
- Language
- Discussion
Taking these two medicines together can cause your blood pressure to drop lower than intended. This might make you feel dizzy, lightheaded, or faint, especially when standing up quickly. Additionally, both drugs can cause drowsiness, which may be more intense when they are used at the same time.
In this article:
Continue reading below
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.
Continue reading below
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.
Patient picks for Drug interactions

Treatment and medication
Can I take Lions mane and Maitake together?
Both Lion's Mane and Maitake mushrooms may lower blood sugar levels and slow down blood clotting. Taking them together might increase the risk of your blood sugar dropping too low (hypoglycaemia) or increase the chance of bruising and bleeding.

Treatment and medication
Can I take Ibuprofen and Naproxen together?
Taking ibuprofen and naproxen together significantly increases your risk of serious side effects, particularly stomach ulcers, internal bleeding, and kidney problems. It can also make your blood pressure rise and cause fluid retention.
Continue reading below
Article history
The information on this page is written and peer reviewed by qualified clinicians.
25 Jan 2026 | Originally published

Ask, share, connect.
Browse discussions, ask questions, and share experiences across hundreds of health topics.

Feeling unwell?
Assess your symptoms online for free
Sign up to the Patient newsletter
Your weekly dose of clear, trustworthy health advice - written to help you feel informed, confident and in control.
By subscribing you accept our Privacy Policy. You can unsubscribe at any time. We never sell your data.