Negril is a safer destination in comparison to other resort areas of the Caribbean.  Crime can be a problem near the resort areas.  It is generally safe to walk along the beach, although you may be occasionally hassled by vendors, who range from perfectly polite and unobtrusive to aggressive and belligerent.  Do not be surprised to be offered marijuana for sale; if you are not interested, a simple "No, thank you" should do. Never walk around outside the resort gates, but if you must, trust your own judgement.

Mosquitoes can be bothersome, particularly around dusk.  Be sure to use bug spray to avoid being bitten.  Malaria is not an issue here, so there is no need to worry if you are bitten, and there is no need to use anti-malarial treatments.  In addition to mosquitoes, sand flies are a similar sort of pest.  They also come out after dark, usually on the beaches, and their bites can also be prevented with bug spray.  The last creatures to be aware of are the centipedes that you may encounter if you go hiking in the woods.  They do bite, so do not attempt to handle them.

This is a sunny, island destination so standard sun and water precautions should be taken.  Use plenty of sunscreen to avoid being burned, and be sure to keep a close eye on children near the ocean.