I had this crazy problem where one eye was mega red. Looked like a pink eye thing. well, went to the doctor and he prescribed this $100 bottle of eye drop. found out it was the same anti-histamine drops you can get over the counter, but prescription strength. Basically I read the instructions and it said that it only will work till you body builds an immunity to it, so watch out. Visene and the like will only work for a minute till your body either depends on it, or rejects it and does nothing to fix your problem.