Allopurinol during Pregnancy & Breastfeeding

by on June 13, 2012

The US Food and Drug Administration has various categories detailing the effects of medications in pregnancy on the growing fetus. The FDA has categorised allopurinol (Zyloprim, Aloprim) as a class C medication. This means that there have not been any human studies of adequate quality demonstrating the effects of allopurinol on the fetus, but animal studies show that there may be harm caused by this medication.  However, the certainty of harm to a human baby is not known because animals may be affected by medications in a different way to humans.

Allopurinol during Pregnancy

The main disease that allopurinol treats is gout; this a condition in which a person’s joints become very painful and swollen.  Gout is usually a disease of middle-aged to elderly males who frequently are overweight, smoke and eat a diet high in meat. It does not usually occur in young women, so it is unlikely that a pregnant woman would be taking, or require allopurinol treatment. However, if allopurinol is needed by a mother due to gout or renal stones, then it should only be used during pregnancy if the doctor decides that the benefits to the mother’s health outweigh the risks to the fetus’ development.

Animal studies have shown that some harm may be done to offspring by taking allopurinol during pregnancy, but this is at doses much higher than would be given in humans.

Allopurinol during Breastfeeding

Similarly, it is unlikely that allopurinol would be given to a breastfeeding mother, because a young woman would be relatively unlikely to develop gout. If a mother takes allopurinol then this medication does become present in her breast milk, but whether this causes a harmful effect to her child is unknown. Once again, the doctor will consider the risks to the child and benefits to the mother when deciding whether to continue allopurinol treatment during breastfeeding.

If you are breastfeeding and are taking allopurinol, then there are ways that you can minimise the effects of this on your child. You should speak to your doctor about taking the lowest possible dose of allopurinol that still controls your symptoms. In addition, it is important to plan at what time of day you will take the medication. If you take it at the beginning of the longest possible time before the child feeds again, for example just after a feed, or when the child is asleep, then the majority of the medication will have cleared from your body before the child feeds again. This will ensure that your baby is exposed to the minimum amount of medication, whilst you still get the drug that you need.