Warning!
- This medicine may colour your urine. This is harmless.
- This medicine may cause dizziness, sleepiness and double or blurred vision, particularly when starting treatment or after dose increases. This means the medicine may reduce your ability to drive or operate machinery safely. Do not drive or operate machinery until you know how this medicine affects you and you are sure it won't affect your performance. Drinking alcohol while taking this medicine can make your vision blurred.
- This medicine can sometimes cause pain or difficulty passing urine, or not being able to urinate at all (urinary retention). This is most likely in the first eight weeks of taking this medicine. You should tell your doctor straight away if you experience any of these problems.
- This medicine can cause mental health problems such as confusion, psychotic disorders and hallucinations in some people. These problems generally tend to happen in the first eight weeks of taking this medicine if they are going to occur. You should consult your doctor if you think this medicine is affecting you in this way.
- There may be a small increased risk of depression, suicidal thoughts and behaviour in people taking antiepileptic medicines such as retigabine for any condition. For this reason, it is very important to seek medical advice if you or someone else taking this medicine, experience any changes in mood, distressing thoughts, or feelings about suicide or self-harm at any point while taking this medicine. For more information speak to your doctor or pharmacist.
- Some people taking this medicine for long periods of time have experienced discolouration of the tissues in the eyes, including the retina. In some cases this was linked with problems with vision. You will need to have an eye examination before starting treatment and every six months while you are taking this medicine to make sure it is not affecting your eyes. Tell your doctor if you notice any changes in your eyes or vision while you are taking this medicine.
- Long-term use of the medicine has also caused a blue/grey discolouration of the skin, lips or nails in some people. You should let your doctor know straight away if you notice anything like this.
- People over 65 years old.
- People with moderate to severely decreased liver function.
- People with moderate to severely decreased kidney function.
- People who have problems passing urine, for example due to an enlarged prostate gland. (This medicine can make these problems worse, particularly in the first eight weeks of treatment.)
- People with congestive heart failure.
- People with poor functioning of lower chambers of the heart (ventricular dysfunction).
- People with low levels of potassium in their blood (hypokalaemia).
- People with low levels of magnesium in their blood (hypomagnesaemia).
- People with a personal or family history of an abnormal heart rhythm seen on a heart monitoring trace (ECG) as a 'prolonged QT interval'.
- People taking medicines that can cause a prolonged QT interval on an ECG (see end of factsheet for examples).