Spironolactone is generally safe and well tolerated and can be taken for years if needed often with minimal side effects. It is taken once a day. Common side effects include breast tenderness or enlargement, irregular menstrual periods and a drop in blood pressure (which can cause dizziness). Uncommon side effects include drowsiness, fatigue, headache, loss of libido (sex drive), confusion, rashes, abnormal blood count and high potassium levels.
Because high potassium can be dangerous it is essential to have blood tests performed prior to starting treatment, after 2 weeks of treatment then after a further 3 months. If these blood tests cannot be performed then it is not safe to continue the treatment. Once established on treatment blood tests can be performed every 6 months. It is essential not to become pregnant whilst taking spironolactone as it can cause birth defects. As for any medication it is essential to read the information leaflet that comes within the packaging and contains a full list of all recognised side effects.
The British Association of Dermatologists has produced a helpful Patient Information Leaflet on Spironolactone and it is important that you read this before starting treatment.