Identifying Skin Rashes
There are many reasons skin rashes occur, from insect bites to serious medical conditions. If you experience a rash, it's important to identify its cause so you can seek appropriate treatment.
Psoriasis, shown here, is a chronic skin condition that usually affects the scalp, knees and elbows. It produces a rash that is characterized by:
- Thick, dry plaques of skin
- Crusty, oily patches
The condition usually affects the scalp, the T-zone on the face and, sometimes, the genitalia.
Atopic Dermatitis or Eczema
The rash is characterized by:
- Dry, red patches
- Thickened skin from repeated scratching
Heat rash often appears during bouts of hot, humid weather that leads to sweating. The rash can appear anywhere on the body, but especially on areas where the skin folds, such as the neck, belly, groin, buttocks and under the breasts.
The rash is characterized by:
- Clusters of red, pinpoint bumps
- General inflammation
Pityriasis rosea is a skin rash that can affect people in any age group but tends to occur in people between the ages of 10 and 35. This rash typically goes away by itself within six weeks.
Pityriasis rosea is characterized by:
- A large, slightly raised scaly patch called the herald patch
- Additional smaller scaly patches that appear within a few days to weeks of the herald patch
- Significant itching
The cause of lichen planus is unknown, but is often attributed to an allergic reaction. This common rash appears in the form of single or clustered skin lesions. Over the counter antihistamines and topical ointments may help mild cases, though more severe rashes may require corticosteroids or ultraviolet light therapy. A biopsy may be required to confirm diagnosis.
- Flat rash
- Sharp borders surrounding rash
- Tiny red bumps
- Intense itching
- Bumps that turn into fluid-filled blisters
- Blisters that break open and scab over
The rash usually appears on the back, abdomen or face, and it can spread over the entire body. Outbreaks usually last two to four days, and then healing begins. Once a person has had chickenpox, he or she is susceptible to an outbreak of shingles later in life.
Shingles are caused by the same virus (varicella-zoster virus) that causes chickenpox. Once a person has had chickenpox, the virus remains dormant in her system. For reasons that aren't completely understood, the virus can reactivate and cause a painful condition known as shingles.
The pain can be felt before any sign of the rash, but the rash is characterized by:
- Burning pain
- Small blisters on a base of inflamed skin
- Band-like rash pattern on one side of the body
Measles is a childhood infection that was once very common but can be prevented due to vaccinations. A measles infection often causes a rash seven to 14 days after exposure to the virus.
A measles rash:
- Typically starts on the face, then spreads down the arms and trunk, legs, and finally feet
- Can contain small flat red lesions or raised red bumps that merge into each other
- Is itchy
Scarlet Fever Rash
Scarlet fever is an infection caused by bacteria that produces a sunburn-like rash in the face and possibly other areas of the body. This is usually treated with antibiotics.
- Affected area feels like sandpaper to the touch
- Rash area turns pale when pressure is applied
- Skin folds turn a deeper red than surrounding rash
- Tongue appears red and bumpy
- Tongue may develop a white coating in the first stages
A staph infection is caused by Staphylococcus bacteria. This type of bacteria is often carried on the skin but when there is an injury, the bacteria can enter the system and cause an infection.
Different staph skin infections include boils, impetigo, scalded skin syndrome, and cellulitis. This is a picture of a staph infection in a surgical wound.
- Purulent discharge
- Wound not healing normally
- Abnormal smell
Impetigo is a very contagious skin infection that is more common in infants and children. It usually occurs on exposed parts of the body like the face or the arms and legs.
This rash is characterized by:
- One or many fluid- or pus-filled blisters clustered together
- Oozing and crusting
- Swollen lymph nodes near the point of infection
- Tiny pimples or bites
- An S-shaped pattern
- Irritation and itching
- Crusty scales (In cases of Norwegian scabies)
The mites that cause scabies typically inhabit skin crevices.
Hand-foot-mouth disease is a common viral infection in children. It is most commonly caused by coxsackievirus.
This condition is characterized by:
- Painful, blister-like lesions on the tongue, gums, and inside of cheeks
- A red rash which is typically not itchy
- A rash with either flat red spots, raised red spots, or occasionally with blisters
- A rash that occurs on the palms, soles of the feet, or buttocks
Lyme disease is caused by the bacterium Borrelia burgdorferi which is passed onto humans by tick bites.
One of the early signs of infection is a skin rash. Indicators include:
- A small bump at the tick bite site
- Over the next few days, the bump develops into a bull's-eye rash
- Rash expands over days to weeks
- Rash accompanied by fever, chills, headache, body aches, and fatigue
Fifth disease is a viral infection caused by human parvovirus B19. It typically occurs in pre-school and school-age children during the spring.
The rash associated with this condition:
- Usually starts on the cheeks and is bright red
- Then appears on the arms, trunk, and legs
- Clears from the center outward
- Lasts for 1-2 weeks
Ringworm is not caused by a worm; it's actually a type of fungal infection. It produces a very unique rash that is characterized by:
- A raised ring of reddened skin
- Ring is usually scaly
- Ring spreads outward
Ringworm can appear on the skin, scalp and nails.
Poison Ivy, Oak or Sumac
Contact with poison ivy, oak or sumac plants can lead to a rash also known as contact dermatitis. This rash is characterized by:
- Red streaks on the skin
- Raised blisters that weep
- Intense itching
The rash can last from one to three weeks if left untreated. However, your doctor can recommend products to help the rash heal more quickly.
Hives can appear anywhere on the skin, usually as the product of an allergic reaction. The rash is characterized by:
- Red welts with a lighter center
- Intense itching
- Welts that come and go in various locations
The rash usually runs its course in about 24 hours.
Swimmer's Itch (Cercaria Dermatitis)
Cercaria dermatitis or swimmer's itch is an allergic reaction to certain parasites found in fresh or salt water. This condition usually resolves on its own in a few days.
Signs and symptoms include:
- Itching that can start a few hours or up to a few days after swimming
- Red, raised rash
Intertrigo is a skin inflammation that occurs in moist, warm areas of the body such as skin folds. It can be aggravated by moisture, bacteria, yeast, or fungi in the top layers of the skin. It can be a common complication in diabetes or obesity; it can also appear as diaper rash in infants.
Signs and symptoms include:
- Red or reddish brown rash
- Cracked or crusty skin
- Itchy or raw or oozing areas located in a skin fold
- Foul odor
Drug Allergy Rash
Allergic reactions to medications and other substances may cause a widespread rash over the body. Discontinue medications if they cause a rash and discuss with your physician.
Drug allergy rashes can be characterized by:
Insect Bite Rash
Insect bites can often cause itchy or painful rashes. Here a wasp sting has caused a red rash. Although many insect bite rashes can be resolved at home with cool compresses or over-the-counter antihistamine creams, rashes that are severe or that get worse instead of better should be evaluated by a doctor for possible allergies. Insect bites can be fatal in allergic persons.
Symptoms can vary by type of insect, and not everyone reacts the same way. Symptoms include:
- Itching, sometimes severe
- Burning sensation (depending on type of bite)
Brown Recluse Spider Bite
The majority of spiders in the US are not dangerous to humans - even if you get bitten. For most spider bites, you may have a reaction similar to a bee sting with redness, pain, and swelling at the site. However, there are a few particularly dangerous spider bites, specifically bites from brown recluse and black widow spiders.
A brown recluse spider bite (pictured here) is characterized by:
- Immediate itching and pain at the site
- Fluid-filled blister at the site of the bite will form. Often looks like a bull's eye with several red rings around white areas
- The blister turns into an ulcerated lesion which if not treated, may require skin grafting in up to 10% of cases
- Fever and chills
- Body Rash
Black Widow Spider Bite
Bites by a black widow spider can be quite dangerous.
A black widow spider bite is characterized by:
- Swelling and redness in area of bite
- Muscle and abdominal cramps within 8 hours
- Nausea and vomiting
Consult Your Physician
You should always consult a physician for a proper diagnosis of any skin rash, but looking at images of various rashes may give you some idea of what you might be dealing with.