The drug Allopurinol can strongly influence the effect of many other drugs, therefore it must be clarified with the attending physician before taking it, whether and how other necessary drugs have to be adjusted. Allopurinol has a strengthening effect on the effects of various anticoagulants. Particular attention should therefore be paid to the necessary intake of so-called coumarins (warfarin, marcoumar).
In the course of an application of Allopurinol the daily dose of the anticoagulant should be reduced. In addition, the effect of Probenecid will increase. Probenecid is a drug which (just like Allopurinol) is used to reduce excessive urea concentrations in the blood and therefore serves as a therapy for gout.
Special caution is also advised in patients treated with chlorpropamide, a sulfonylurea used for diabetes therapy. The effectiveness of this drug is also enhanced by the simultaneous intake of Allopurinol. Certain antiepileptic drugs (especially phenytoin), which serve to inhibit the excitability of nerve cells and can thus be used to treat epilepsies, urgently need to be redosed when allopurinol is administered.
Although allopurinol plays an important role in medicine and has achieved great success in the treatment of gout, adverse drug effects (side effects) cannot be ruled out. When prescribing this drug, the treating physician must always weigh up whether the clinical benefit outweighs the risk of side effects. A possible complication associated with taking allopurinol is the occurrence of the so-called Stevens-Johnson syndrome.
According to studies, allopurinol is actually the most common cause of this condition (Stevens-Johnson syndrome). Stevens-Johnson syndrome is a severe drug reaction which is mainly manifested on the skin and is rather rare. In the course of the Stevens-Johnson syndrome, the epidermis (uppermost skin layer) detaches from up to 10% of the body surface.