- Seborrheic dermatitis
- Atopic dermatitis
- Contact dermatitis
- Stasis dermatitis
- Nummular eczema
- Drug eruptions
- Heat rash (miliaria)
- Diaper rash
Since the real question to be answered is what rashes are contagious, the remainder of this short article will address most of those rashes that are considered contagious; not all experts agree on these designations, so readers concerned about a rash are urged to discuss their condition with their physician.
Rashes that are considered by many physicians to be contagious are as follows:
- Molluscum contagiosum (viral)
- Impetigo (bacterial)
- Herpes (herpes simplex, types 1 and 2 viruses)
- A rash caused by Neisseria meningitides (N. meningitides) (bacterial)
- Rash and blisters that accompany shingles (herpes zoster virus)
- Ringworm (fungal) infections (tinea)
- Scabies (itch mite)
- Chickenpox (viral)
- Measles and rubella (viral)
- Erythema infectiosum (viral)
- Pityriasis rosea (viral)
- Cellulitis and erysipelas (bacterial)
- Lymphangitis (bacterial)
- Folliculitis (bacterial)
This list is not exhaustive but covers many of the rashes that people may encounter. The definition of contagious depends on whether the rash itself can be spread or the infection that causes the rash can be spread, so some experts may not agree with the designations above. For example, in some cases, the rash is contagious in that someone can get the rash from another person with the rash. In other cases, a person with a rash may be at risk of spreading the infection that caused the rash (which may not necessarily cause a rash in the person who gets infected).
How will I know if I have a contagious rash?
Often, rashes appear in children and adults. Even though some of the "contagious" rashes have fairly typical presentations (for example, shingles have a reddish rash, usually with blisters, develops on one side of the body along the area supplied by one nerve) but not always.
Consequently, if you have had contact with a person who has a known contagious disease that forms a rash, you should contact a physician. Similarly, if you're concerned about a rash that has developed, a physician and/or dermatologist can help diagnose your skin condition. A conservative way to approach rashes is to consider all of them contagious until proven otherwise.
How do contagious rashes spread?
Most contagious rashes spread from person to person by direct contact. Many of the rashes are itchy and spread when an infected individual scratches the rash and then touches or scratches another individual who is not yet infected. However, some rashes can easily spread by indirect contact; for example, ringworm can be easily spread from the locker room floor to another individual by simply walking on the contaminated floor.
How will I know when I am cured of a contagious rash?
The possible cure of the contagious rash depends on the underlying cause of the rash. For example, once an individual has been appropriately treated with antibiotics for N. meningitidis infection, the rash and the patient usually become noncontagious after about 24-48 hours and the rash slowly disappears. To help determine the underlying cause and cure for your rash, speak with a physician.
When should I contact a medical caregiver about a rash?
In most cases, if an individual has a noncontagious rash or a noncontagious cause of the rash, there is no need to contact a medical caregiver emergently unless the rash and/or underlying cause is rapidly spreading.
If you suspect you have been exposed to a contagious rash, contact your physician early to get appropriate advice and treatment. However, if you know you have been exposed to the rash caused by N. meningitidis, you should contact a medical caregiver emergently. If you have a rash that is shedding or sloughing off patches or large areas of skin, this is considered a medical emergency and the person should be seen quickly in an emergency department.
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Grimm, L. "14 Rashes You Need to Know: Common Dermatologic Diagnoses." Medscape.com. Oct. 19, 2017. <https://reference.medscape.com/features/slideshow/skin-rashes>.
United States. Centers for Disease Control and Prevention. "Meningococcal Disease (Neisseria meningitidis)." Mar. 10, 2017. <http://wwwnc.cdc.gov/travel/diseases/meningococcal-disease>.