Can I take Spironolactone and Potassium together?

Why this happens

Spironolactone is a 'potassium-sparing diuretic' (water tablet). Unlike most water tablets that make you lose potassium in your urine, spironolactone tells your kidneys to hold onto potassium while getting rid of extra salt and water. If you take extra potassium supplements at the same time, the potassium builds up in your body because the kidneys are being blocked from flushing the excess away.

What you should do

You should only take potassium supplements with spironolactone if your doctor has specifically told you to do so and is monitoring your blood levels closely. Avoid using 'salt substitutes' (like Lo-Salt) which are made of potassium chloride. You should also be careful with eating very large amounts of potassium-rich foods like bananas or spinach. Your doctor will likely perform regular blood tests to check your potassium levels and kidney function. Seek medical help immediately if you feel an irregular heartbeat or extreme muscle weakness.

Important precautions

Hyperkalaemia (High Potassium)

Taking these medicines together significantly increases the risk of dangerously high potassium levels in your blood. This can cause life-threatening heart rhythm problems. You must have regular blood tests to monitor your potassium and kidney function.

Pregnancy

Spironolactone should not be used in pregnancy as it has an anti-androgen effect that can interfere with the normal development of a male fetus.

Salt Substitutes

Avoid using 'Lo-Salt' or other potassium-based salt substitutes. These contain high levels of potassium which, when combined with these medicines, can lead to a toxic build-up of potassium in your body.

Food and drink warnings

Alcohol

Spironolactone lowers your blood pressure. Drinking alcohol can increase this effect, making you feel dizzy, lightheaded, or faint, especially when standing up. It is best to keep alcohol intake to a minimum until you know how the medicine affects you.

High-potassium foods (e.g. bananas, oranges, spinach, avocados)

Spironolactone is a 'potassium-sparing' diuretic, meaning it helps your body hold onto potassium. Taking it alongside potassium supplements or a diet very high in potassium can cause your blood potassium levels to become dangerously high (hyperkalaemia). You should avoid consuming excessive amounts of these foods and only take potassium supplements if specifically directed by your doctor while on spironolactone.

Salt substitutes (e.g. Lo-Salt)

Many salt substitutes use potassium chloride instead of sodium. Using these while taking spironolactone or potassium supplements can lead to a rapid and dangerous rise in blood potassium levels. You should avoid these products entirely.

Food (General)

Spironolactone should ideally be taken with food. This helps your body absorb the medicine better and can reduce the chance of feeling sick (nausea).

Liquorice (Natural/Black)

Natural liquorice (containing glycyrrhizic acid) can interfere with how spironolactone works, making it less effective at lowering your blood pressure or reducing fluid build-up. Most 'liquorice-flavoured' sweets are safe, but you should avoid real black liquorice or liquorice root supplements.

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.