WebMD advises against popping or breaking blisters from spider bites or other causes. Instead, it is best to cover them loosely with a clean bandage or leave them uncovered. Additionally, it is important not to apply pressure to the blister.
The Mayo Clinic advises victims of spider bites to wash the area thoroughly with soap and water. A cool compress applied to the area helps to reduce the swelling. Additionally, if the bite occurs on the arms, hands, legs or feet, the bitten appendage should be elevated. The Mayo Clinic suggests that patients take aspirin or acetaminophen if the bite is painful. If the bite itches, patients can take antihistamines to alleviate the symptoms.
If the blister is painful or in an inconvenient location, WebMD suggests washing the area with soap and water, popping the blister with a sterilized needle and gently squeezing out any fluid under the skin. After washing the blister one more time, an antibiotic ointment can be applied, and the affected area can be covered with a sterile bandage.
The Mayo Clinic states that blisters thought to be from spiders are usually from another type of invertebrate. If a spider bite caused the blister, it is important to identify the offending spider if possible to ensure that it is not a species that can cause serious illness.