I hv acne, I used deriva for 3 weeks. I had to expose to sunlight for 5 days with out suns cream. Nw m black. Bt I didn't stop using the cream, ?

Side Effect of Med. Deriva will make your skin extra sensitive to the sun, this means that you should always use sunscreen and limit sun exposure. The first few weeks of use as your skin is adjusting to the treatment you will experience dryness, flaking, scaling, redness and irritation. You may have to use a prescription bleaching to lighten your skin.
Use the cream. If you are fine and still have acne, which probably is whiteheads and blackheads (though it works for pimples too) you should continue to use the cream. It is never wise to get that much sun exposure and not wear sun screen anytime!