Discoloration of the skin, mucosa and nails is sideeffect of

.When nail discoloration is due to zidovudine, patients are usually able to repo if the discoloration preceded or coincided with the initiation of therapy. Another unusual side effect of zidovudine noted by some is a grayish-black discoloration of the tongue. Azidothymidine-induced nail pigmentation Ref Robbins 9/e pg 789