Risk Factors and Causes of Rashes

A personal or family history of allergies or asthma increases the risk for rashes. People who spend a lot of time outdoors are at increased risk for poison ivy, poison oak, and poison sumac; and for rashes caused by insect bites.

Common causes for rashes include the following:

  • Allergic reaction (e.g., resulting from an animal allergy, drug allergy, or food allergy)
  • Bacterial infection (e.g., impetigo)
  • Drug side effect
  • Excessive skin rubbing (friction)
  • Fungal infections (e.g., athlete's foot, ringworm)
  • Insect bites (e.g., tick, flea, spider, mosquito)
  • Parasite infection (e.g., scabies)
  • Prolonged exposure to heat, moisture, or irritants (e.g., heat rash, diaper rash, contact dermatitis)

Certain medical conditions can result in a rash, including the following:

  • Acne (often develops on the face, neck, back, and shoulders)
  • Lupus (commonly causes a "butterfly" rash across the cheeks and under the eyes)
  • Lyme disease (usually transmitted by the bite of an infected deer tick; causes a "bull's eye" rash)
  • Psoriasis (typically causes round, red lesions with sharply defined edges and overlying silvery white scales [called plaques]; usually begins as small spots that progressively involve very large areas)
  • Rosacea (often occurs on the forehead, nose, and chin)

Publication Review By: Stanley J. Swierzewski, III, M.D.

Published: 02 Jan 2007

Last Modified: 27 Jul 2010