The answer, I think, is that it varies widely from person to person.

I'm on a fairly high dose of HU (ten 500 mg capsules / week). Other than scaring myself silly about taking the first capsule, I haven't had any side effects at all.

From postings here, I learned to never take HU on an empty stomach, and that drinking plenty of water during the day is beneficial.

This is the perfect place for your questions and concerns -- someone here will have good advice for you!