In most adults, a rash can be mild and resolve on its own. But if you have other symptoms, such as fever, pain, or a rash that spreads, you may need urgent medical care.

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Rashes can cause irritation and discomfort. Rashes in very visible places such as your hands or face might even cause embarrassment. Fortunately, most rashes are mild and not a cause for concern. You can generally treat a rash with over-the-counter (OTC) remedies.

However, there are rashes that a medical professional should look at. These rashes might be a sign of an infection, allergic reaction, or disease. You can read 12 common signs a rash might be a sign of something more serious below.

An area on your skin that is itchy, irritated, and swollen is called a rash. A rash can be raised, bumpy, blistered, or patchy.

Rashes can present differently depending on your skin tone. People with lighter skin often see rashes that are pink, red, or purple. People with darker skin might develop rashes that are white, gray, or darker than the surrounding skin.

Rashes can be caused by many things including:

  • underlying health conditions
  • stress
  • sun exposure
  • allergic reactions
  • weather

Rashes are very common. Many types of rash are mild and can be treated with OTC medications. For example, contact dermatitis is a rash you get when your skin touches something that causes it to become itchy and irritated.

If you’ve ever gotten a rash from a new laundry detergent, lotion, or soap, your rash was likely contact dermatitis. A contact dermatitis rash will be inflamed and itchy. It will generally be contained to the part of your skin that touched the irritant.

Avoiding the item in the future and using an OTC anti-itch cream is normally enough to treat contact dermatitis.

Other common rashes in adults include:

  • Hives. Often caused by an allergic reaction to medications, foods, or beverages, hives appear as raised, itchy, splotches and often spread rapidly.
  • Shingles. Caused by the same virus that is responsible for chicken pox, shingles is often painful forming patches of skin with bumps that blister and itch. Anyone who has ever had chicken pox is at risk of developing shingles.
  • Chronic rashes. Conditions such as eczema or psoriasis can cause chronic rashes that can flare when triggered. A dermatologist can help you manage these conditions.

Sometimes, a rash is a sign something serious is going on with your body. It’s a good idea to keep an eye on any rash you develop and watch for these signs. Seek medical care if any of them develop.

1. You have a fever

A fever is a key sign that rash should be looked at by a doctor. It could be a sign of an allergic reaction. A fever along with your rash could also indicate an infection such as:

2. The rash is spreading

A rash that is spreading is another sign it’s time to seek medical care. A rash that is spreading quickly might be a medical emergency. It’s best to go to an urgent care center or the emergency room if your rash is spreading rapidly.

If your rash is spreading slower but is spreading over your body, it’s still a good idea to get it looked at. It might be a warning that your rash is caused by an allergic reaction or an infection.

3. The rash area hurts

A painful rash should be looked at by a medical professional. It could be infected or a sign of conditions such as shingles.

It’s best to also keep an eye on any rash that isn’t painful but that is tender when you press on it. This could be a sign of infection, and you’ll want to have it checked out if it doesn’t resolve after a day or so.

4. The rash came on suddenly

A rash that comes suddenly may be an allergic reaction to a medication. Sometimes, a rash can develop in the first few weeks after you start a new medication. Let a medical provider know about this side effect as soon as possible.

It’s important to be careful when a rash is caused by an allergic reaction to mediation. This kind of reaction can lead to difficulty breathing and may become a medical emergency.

5. The rash is beginning to blister

Sometimes rashes caused by sun exposure or poison ivy can blister. These rashes generally heal on their own in most cases.

However, unless you’re sure your rash was caused by the sun or poison ivy, any rash that blisters should be looked at by a doctor. It could be a sign that your rash is a severe allergic reaction to a medication or caused by an autoimmune condition called pemphigus vulgaris.

6. You see signs of infection in the rash

Rashes damage the surface of your skin. This can make it easy for infections to develop, especially if you scratch the rash area. An infected rash should be looked at by a medical professional. Signs a rash is infected:

  • pain
  • warmth
  • swelling
  • crusting over of rash bumps
  • yellow discharge
  • green discharge
  • a bad smell

7. You have difficulty breathing

This is a medical emergency. Call 911 or seek care right away. A rash and difficulty breathing can be signs of a serious allergic reaction. This might happen when you eat or drink something you’re allergic to.

When to call 911

A rash can be a sign of a serious medical emergency called anaphylaxis when it happens along with other symptoms. Call 911 if you have a rash and any of these is occurring:

  • It is spreading rapidly.
  • You’re having trouble breathing.
  • You have a high fever.
  • You feel lightheaded or dizzy.
  • You’re nauseous.

It’s best not to drive yourself in any of these scenarios. If your reaction is anaphylaxis you could become unconscious in just a few minutes.

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8. The rash looks like large purple patches

A rash that looks like large purple patches or dark bruises can be a sign of a serious condition. It could be a warning sign of an infection spreading throughout your body or of a blood clotting problem. It could also indicate a condition called vasculitis that causes your blood vessels to become inflamed.

A medical professional can determine what’s causing this rash and start treatment.

9. Bruises are forming in or around the rash

A rash with bruising or swelling around it might have been caused by an insect bite. It’s a good idea to seek medical care if you notice this symptom. The bruises and swelling are a warning that that poison from the bite could be cutting off blood flow to the area.

10. The rash is in a circle shape

A circular-shaped rash could indicate Lyme disease. Caused by ticks, Lyme disease normally causes a rash that resembles a bull’s-eye and symptoms similar to the flu. Antibiotics are the primary treatment for Lyme disease, so you’ll need to visit a medical provider for a diagnosis and prescription.

11. You’ve had the rash for longer than a week

A rash that persists for more than a week is worth getting looked at by a medical professional. There might be a reason your body is having trouble healing the rash. Plus, even if your rash is mild, a medical professional can give you tips to treat it at home.

12. The rash is causing you discomfort or concern

It’s a good idea to get any rash that is causing you to feel significant discomfort or concern checked out by a dermatologist or other healthcare professional. While it might be simple contact dermatitis, it’s still a good idea to consult a doctor.

Rashes are a common skin condition. Most rashes are temporary and clear up on their own. However, a rash can be a sign of something more serious.

Allergic reactions, infections, autoimmune conditions, and more can also cause rashes that need to be seen by a medical professional.

Rashes that occur along with trouble breathing, fever, lightheadedness, or nausea, are a medical emergency.