Azathioprine and Photosensitivity

At long last the dismal winter and the long cold spring are behind us and Wimbledon was bathed in glorious sunshine. Delight at the arrival of the summer must, however, be tempered by a note of caution. People taking azathioprine should remember that this drug causes photosensitivity – that is, it increases the effects of sunlight on the skin. To prevent nasty burns and skin rashes, those taking azathioprine for IBD must be cautious about exposing themselves to the sun.  Wear a hat to act as a sunshade, and do not lie out in a bikini on a Mediterranean beach!

Another point to remember is that grapefruit juice contains a chemical which blocks the action of an important drug-metabolising enzyme, cytochrome P 450. This enzyme is found in the liver and also in the wall of the intestine. Drugs such as budesonide which are normally broken down nearly completely in the wall of the gut and in the liver should not reach the circulation in large amounts, and thus are less likely to produce side-effects, compared with other corticosteroids such as prednisolone. The amount of budesonide reaching the circulation however, may be nearly doubled in people who drink grapefruit juice regularly because the enzymes breaking it down are prevented from working properly –  just another point to remember whilst you are relaxing in the lovely countries where citrus fruit are grown!  (Orange and lemon juices don’t cause this problem).

It’s also sensible to try to avoid gastroenteritis or food poisoning which are more prevalent in hot countries because of the flies!  Ideally all food should be freshly cooked so as to kill off all bacteria, and cold cuts and salads, etc, avoided. Peel all fruit yourself, as the insides of fruits are sterile, and don’t drink tap-water (or have ice in your drinks – the bacteria are resistant to freezing and are released as the ice slowly melts!). Drink bottled water, wines and beers. If you do get gastroenteritis, then it is a good idea to drink a sugar and electrolyte solution such as Dioralyte until symptoms settle. This will make a flare of your IBD less likely. If you haven’t taken any Dioralyte with you, then you can make an adequate substitute by adding a tablespoonful of sugar and a level teaspoonful of salt to a pint of boiled water.

Bonnes vacances! provides general information only and should not be regarded as a substitute for medical advice from your own doctor or healthcare provider.
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