Q. I am 56 years old and I am a housewife. Previously, I was taking Atenolol 50mg for my high blood pressure. This was changed to Simvastatin or Simvor 10, alongside Nifedipine LA 30mg.

Why is my urine very yellow after taking Simvor and Nifedipine ?

Can they cause this side effect?

A. Passing dark or yellow urine may be non-specific or due to dehydration in a healthy individual. However, in your case, this could be related to the cholesterol-lowering medication, Simvastatin, which you are taking.

This class of medication can infrequently cause side effects such as muscle tissue breakdown. The breakdown product can then spill into the urine and make the urine dark in colour.

I would like to emphasise that this side effect is exceedingly rare. Studies show that only about one in 100,000 individuals taking statin have this complication. Another uncommon side effect of this medication is liver injury, which can also result in dark urine.

Therefore, it is important for you to inform your doctor, as soon as possible, that you are passing dark yellow urine after taking Simvastatin so that these two serious side effects can be investigated and excluded.

In the meantime, it may be prudent to stop Simvastatin, while waiting for the investigations and consultation with your doctor. You can restart later once these have been cleared.

DR STANLEY LIEW, CONSULTANT ENDOCRINOLOGIST, RAFFLES HOSPITAL

For appointments at Raffles Hospital, please call 6311-1222