Some people take vitamin A by mouth or as a shot into the muscle for treating vitamin A deficiency. It is also taken by mouth to reduce complications of diseases such as malaria, HIV, measles, and diarrhea, and to improve growth, in children with vitamin A deficiency.
In extreme cases, not getting enough vitamin A can lead to complete blindness or dying corneas, which are characterized by marks called Bitot's spots ( 7 , 8 ). Dry eyes, or the inability to produce tears, is one of the first signs of vitamin A deficiency.