Rashes are mysterious. Some are minor and pose no threat, while others serve as a warning that there’s a potentially severe or life-threatening issue happening. Unfortunately, it isn’t always easy for the untrained eye to know the difference.
But there are some telltale signs that there may be more to your rash than meets the eye. In some cases, you may even need emergency care.
Here’s what you need to know:
When does a rash need medical attention?
Rashes caused by irritation or minor medical issues typically clear up quickly on their own. But if there’s a more serious underlying cause, you’ll want to get medical care as soon as possible.
Have your rash evaluated by a health care professional if:
You also have symptoms of a severe allergic reaction
Rashes can sometimes accompany other signs of anaphylaxis — a life-threatening allergic reaction. Anaphylaxis requires emergency medical treatment.
Call 911 immediately if you experience:
- Rash that develops and spreads quickly
- Shortness of breath
- Swelling of your face or throat
The rash covers most or all of your body
A new, widespread rash can be a sign of a more severe issue. If the rash spreads quickly, it could be an allergic reaction.
But rashes that spread slowly should also be examined. Some viral infections and other conditions may involve a full-body rash. Your primary care physician (PCP) can help diagnose the underlying issue and start treatment quickly.
You also have a fever
If you have a fever of 100 degrees Fahrenheit or higher, there’s a good chance your body is fighting something off. But when you combine that fever with a rash, it narrows the list of possible infections.
Conditions whose symptoms may include a fever and a rash include:
- Measles
- Mononucleosis
- Scarlet fever
- Shingles
There are signs of infection
An underlying viral infection can cause a rash. But if you can’t resist the urge to scratch, you can also develop a bacterial infection at the rash site.
Signs of an infected rash include:
- Crusting
- Red streaks near the rash
- Swelling
- Tenderness
- Warmth in that area
- Yellow or green liquid or pus
The rash is painful
Rashes can be itchy, annoying and uncomfortable. But a painful rash can signify a more severe underlying virus, such as shingles or genital herpes. Treatment with an antiviral medication may reduce symptom severity and duration of those viruses — so the sooner you start, the better. Viruses such as these can cause chronic pain and ongoing issues if left untreated.
The rash is circular or resembles a bull’s-eye
If your rash looks like a bull’s-eye or appears round, it could be a sign of:
- Ringworm, which is a fungal infection
- Lyme disease, which is spread by ticks and can cause a reddish rash and flu-like symptoms
Both conditions require medical attention. When you detect Lyme disease early, antibiotics may prevent it from spreading throughout the body. If left untreated, ringworm can spread and cause additional skin disorders.
The rash blisters
Rashes caused by poison ivy or sunburn can blister but don’t always require medical care. If you know those things didn’t cause your rash, or the blisters appear near your eyes, in or around your mouth, or on your genitals, you should have the rash looked at by a health care provider.
Blistering and open sores can hint at an autoimmune condition or virus such as chickenpox, shingles or genital herpes — all of which necessitate a visit to your PCP. But a blistering rash along with swelling and flu-like symptoms may suggest toxic epidermal necrolysis — a severe drug reaction requiring immediate attention.
You also have joint pain
Some autoimmune diseases cause joint pain and a rash. If you have both, it could be symptomatic of conditions such as:
- Lupus: Skin symptoms include thick, scaly patches, dark or light spots, or a rash that spreads across the face in the shape of a butterfly. The disease also causes sun sensitivity — scales or a ring-like rash may develop after sun exposure.
- Psoriatic arthritis: Raised red patches of skin with thick silver scales may be painful and itchy. Skin problems are the first sign of psoriatic arthritis for up to 85% of people with the condition.
- Rheumatoid arthritis: Inflammation causes a rash of small, red pinpoints. In more severe cases, skin ulcers can develop on the legs.
The rash looks like a bruise
You’ll want to pay attention to rashes that are purple in color. A rash resembling a bruise could be a sign of:
- Blood clots
- Infection spreading
- Vasculitis
If bruises form around an existing rash, it might be the poison from a bug bite cutting off the blood flow in that area. Consult your PCP to see if there’s cause for concern.
The rash occurs in the folds of your skin
A rash that develops in skin folds — like between your fingers, in the armpit, or under your belly or breasts — may not be a rash at all. It might be a fungal infection called intertrigo.
Intertrigo occurs when the skin in these areas rubs together. The friction causes moisture and warmth that invites yeast, bacteria and fungus. Your PCP may prescribe a steroid or antifungal cream to fight the infection.
Your rash gets worse or doesn’t heal
Most rashes heal or show noticeable signs of healing within a week. But if you’ve had a rash longer than that or the symptoms have worsened, check in with your physician.
Tips for treating a rash at home
If your rash doesn’t require medical attention, you must be patient while it heals. During that time:
- Air it out: Expose the rash to air whenever possible.
- Be gentle with the affected area: Use gentle cleansers and pat your skin dry after bathing. Avoid scrubbing or scratching the skin to reduce the risk of infection.
- Soothe the itch: Apply 1% hydrocortisone cream, take an oral antihistamine or soak in an oatmeal bath.
