13 most common causes
What is an itchy rash?
When your skin is irritated or inflamed, you can break out into an itchy rash. The culprit can be anything from a bug bite to a new type of skin lotion or exposure to poison ivy.
It can also be caused by an inflammatory condition like eczema or psoriasis, or fungal infections of the skin.
An itchy rash can be treated with an over-the-counter (OTC) hydrocortisone cream or an antihistamine like Benadryl to relieve minor itching. A minor rash may go away on its own. But if it doesn’t improve, gets worse, seems to be spreading, or if you also have a fever, you may need to see a doctor.
1. Contact dermatitis
- Itchy rash
- Red bumpy or scaly rash
- May be confined to one area of the body
Contact dermatitis is an allergic reaction on the skin. It is usually mild, but can be itchy or uncomfortable. It can be caused by contact with things like jewelry (nickel or gold), latex, or an ingredient in skincare products.
The rash usually appears a few days after starting the new product. It looks like red bumps or scaly red patches and can be very itchy.
The rash usually goes away after avoiding the allergen. Still, it may take several weeks for the rash to completely disappear. Make note of any new products that you have put on your skin and immediately stop using them.
Over-the-counter hydrocortisone cream may also help control the itch. Also, switch to hypoallergenic and unscented products.
If the rash doesn’t go away or seems to get worse, see a doctor. A doctor may do patch testing to try to figure out what you’re allergic to. And prescribe a prescription topical steroid for the itching.
Patients often think that they cannot develop an allergic contact dermatitis (a skin allergy) to a product that they have used for years. This is simply not true. You can develop a skin allergy to a product at any point in time. This is often very surprising for patients to hear. It often takes some convincing. —Dr. Lauren Levy
2. Poison ivy or poison oak
- Itchy red rash running in a straight line
- Sometimes overlying blisters
When your skin touches an oily resin called urushiol—in poison ivy, poison oak, and poison sumac—you can develop an itchy rash. It can last for weeks.
It’s also possible to get poison ivy if your clothes touch the plant and you touch your clothes. You can also get it from touching a pet that has the resin on their fur.
If you think you were exposed, shower as soon as you come in from the outdoors to minimize the amount of urushiol on your body.
Poison ivy will go away on its own. At-home care, including anti-itch cream (Sarna), oatmeal baths, hydrocortisone cream, and antihistamines, can help relieve the itching.
If the rash does not go away or is extensive, see your doctor. They may prescribe a stronger prescription topical steroid or oral prednisone. If the rash is severe, your doctor may give you a steroid shot.
Seek emergency treatment if you have difficulty breathing.
3. Eczema (atopic dermatitis)
- Red bumpy or scaly rash
- Associated dry skin
Eczema is a chronic (lifelong) skin condition. It is hereditary—you’re more likely to have it if someone in your family has it or if you have a history of food allergies.
You can have eczema flare-ups, which can be itchy and uncomfortable. Dry skin, low humidity, or certain foods and fabrics can trigger flare-ups. Most cases of eczema are diagnosed in childhood but adults and even elderly people can develop eczema.
A dermatologist (skin doctor) can prescribe a steroid-based cream to apply to the rashes. Antihistamines may help with itching, and unscented lotions may help reduce minor rashes.
Taking short, lukewarm showers and using moisturizer may help reduce flare-ups.
4. Insect bites
- Itchy red bumps
- Bumps occurring in groups
Insect bites can cause an itchy rash. Your body is reacting to proteins in the bug’s saliva. It causes an allergic reaction that can vary from mild to severe. In most cases, insect bites are annoying and uncomfortable but not harmful.
Mosquitoes and bed bugs are common causes of intense bite reactions. Children are more likely to have more intense reactions than adults because of their strong immune response.
In some cases, insect bites can trigger more serious illnesses, such as tick bites and Lyme disease. Check for unusual patterns in the rash. For instance, some tick bites may be accompanied by a rash that looks like a bull’s eye. Bed bug bites appear in clusters.
It is important to recognize bed bug bites because your home needs to be thoroughly examined and exterminated to get rid of the bugs.
See a doctor if the rash doesn’t go away, the itching is severe, or the rash seems to be getting worse. An ice pack, OTC anti-itch cream (Sarna), hydrocortisone cream, or antihistamines can help relieve the bites and itching.
- Red welts on your skin
- Itchy skin
- Welts that move around the body
Hives are red, itchy welts on your skin. They usually last for less than 24 hours and then show up in a different area. They can be very itchy and frustrating.
There are many causes of hives. They include an allergic reaction to food, medication, a viral infection, or an autoimmune disease. In most cases, the cause of the hives is unknown (this is called idiopathic).
While minor hives are not an emergency, sometimes hives can be part of a serious allergic reaction. If you notice swelling of your lips or tongue, have trouble breathing, or have diarrhea with an itchy rash, go to the ER.
Hives can be treated with OTC antihistamines. If they don’t get better in about a week or interfere with your daily life, see a doctor who can help figure out the cause and prescribe medications to help them go away faster.
Many rashes in dermatology are idiopathic. This means there is no known cause and it just happens. This is especially true for hives. The good news is the treatments will work and help you feel better even if the trigger is never discovered. —Dr. Levy
6. Heat rash
- Red itchy bumps on the skin
- Bumps may be fluid-filled
A heat rash occurs in hot weather when your sweat ducts get blocked, trapping sweat under your skin. It usually appears in areas that are covered by clothing, such as the chest and back. It’s also common in infants and children, especially on their shoulders, necks, and chest. It can also be caused by a high fever.
Heat rashes usually disappear after you’ve cooled off. If the rash doesn’t go away after a few days, is hurting, or is oozing pus, see a doctor.
According to the American Academy of Family Physicians, you can reduce your chance of getting heat rash by wearing lightweight cotton clothing.
- Many small pink or red bumps surrounding hair follicles
- Itch, pain, or burning
- Bump may leak white fluid or contain pus
Folliculitis is inflammation of the hair follicle. There are two main causes of folliculitis: an infection and an irritation. It can occur on any part of the body that has hair.
- An infectious folliculitis is commonly caused by the bacteria Staphylococcus aureus (known as Staph). The bacteria enters the hair follicles through open skin. It causes the bumps, which are often filled with pus. The area may become painful.
- An irritant folliculitis occurs from repeated trauma of the hair follicle. It causes inflammation around the hair follicle, but there isn’t an infection. Instead of pus, there is often a clear liquid inside the bumps. The bumps can be painful, burning, or itchy.
Sometimes, folliculitis gets better on its own. Not shaving and avoiding skin-care products for several days can clear it up. OTC benzoyl peroxide wash can help treat bacterial folliculitis.
If it does not improve or if it gets worse, see a dermatologist. Treatment may include an oral or topical antibiotic or a topical steroid lotion.
- Red itchy rash in a circular pattern
- Scaly skin at the edge of the rash
Ringworm is a fungal infection that can show up anywhere on the body, including the scalp. You can catch it from direct contact with a person who has the rash or from objects that person has touched. Pets can carry the fungus as well.
Ringworm is a very red, scaly rash in a ring shape. The skin may be clearer in the middle. The rash can be extremely itchy.
OTC antifungal cream like terbinafine (Lamisil) can help clear the rash. See a doctor if the rash doesn’t clear up within 2 weeks or is interfering with your quality of life. You may need prescription medication. If you keep getting ringworm, make sure to have your pet checked out as well.
9. Athlete’s foot
- Red itchy rash on feet or ankles
- Flaky or peeling skin on feet
Athlete's foot is a common rash caused by fungus that invades the foot. You can get the fungus from public floors in the locker room, gym mats, or indoor pools. (That’s why it’s called athlete’s foot.) The rash can be very itchy. You may have red and scaly skin on the feet and possibly toenail fungus.
OTC antifungal creams can relieve athlete’s foot. But you may need prescription oral antifungal medication.
The fungus can live on shoes, so use a sanitizer on your shoes to prevent the rash from coming back. Also, wear shower shoes in shared spaces.
If you have tinea pedis (athlete’s foot), put on your socks before putting on your underwear. This will help prevent the transfer of the fungus on the foot to the groin area. If you have poison ivy, avoid eating cashews and mangos. They both have allergens that cross react with urushiol and can make your poison ivy rash worse and last longer. —Dr. Levy
10. Jock itch
- Red itchy rash around genital or buttock area
- Spares the scrotum
Jock itch is a fungal infection that typically occurs around a man’s genital and buttocks area but usually doesn’t affect the scrotum.
Jock itch can worsen when you wear tight fabrics or clothing. The rash may have a circular shape which extends to the inner thighs.
OTC antifungal medications may help. Severe cases may need a prescription oral medication.
Change out of gym clothes and shower right away to help prevent jock itch. The fungus likes warm and moist environments.
- Extremely itchy red bumps
- Often occurs around the belly button, between fingers, and around the wrist
- Itch may last longer than the rash
Scabies is a contagious infestation by the human itch mite, according to the Centers for Disease Control and Prevention. This microscopic mite burrows in human skin and causes an extremely itchy rash.
If you think you have scabies, see a dermatologist. It is treated with a topical anti-parasite medication called permethrin or an oral anti-parasite medication called ivermectin. Your doctor may prescribe topical steroids to help with itching. The itch can last for several weeks after the mite has been treated (called post-scabetic dermatitis).
Because scabies is so contagious, wash all of your clothing and linens in hot water. Anyone you live with also needs treatment, as people can be carriers of scabies without having symptoms.
- Red scaly plaques on the skin that can be itchy
- May be associated with painful joints
Psoriasis is an autoimmune disease, in which your immune system attacks your skin (and sometimes joints).
Psoriasis causes red scaly plaques commonly on the elbows and knees. The scale is a white-silver color that may bleed when picked.
There may be a red scaly rash in the scalp. And your nails may be brittle or look stained (known as oil spots). If you also have joint pain and stiffness, you may have a condition known as psoriatic arthritis.
Although the exact cause is unknown, it tends to run in families, so it is probably genetic. Risk factors for psoriasis include heart disease, diabetes, metabolic syndrome, obesity, alcohol consumption, and smoking.
Treatments include topical steroid creams, phototherapy, and injectable or oral biologic medications that help control the immune system. Losing weight, controlling blood sugar, reducing stress, and not smoking may help.
13. Drug allergy
- Generalized red rash with itch
- Usually starts 1 to 2 weeks after starting a new medication or increasing the dose of a medication
Drug rashes are allergic reactions to medications, particularly antibiotics and blood pressure medications, or diuretics. They occur 1 to 2 weeks after starting a new medication or increasing the dose of an existing medication.
The rash appears as red bumps that spreads from the chest and back to the rest of the body. It can be extremely itchy.
Treatment for drug rashes include stopping the medication. Prescription topical steroids can help with itching and making the rash go away faster.
After stopping the medication, it usually takes 10 to 14 days for the rash to completely go away.
Avoid taking this medication again in the future and let all of your doctors know about your reaction. For more serious drug rashes, oral steroids may be needed.
Other possible causes
While a number of conditions can cause an itchy rash, an itchy rash may not be a primary symptom. These include:
- Pityriasis rosea
- Bullous pemphigoid
- Lichen planus
- Chicken pox
- Body lice
When to call the doctor
It’s important to monitor itchy skin along with any other symptoms. Call your doctor if:
- Your rash is interfering with your quality of life, including sleep.
- OTC creams don’t provide relief.
- The rash seems to be growing or getting worse over time.
Should I go to the ER for a red itchy rash?
You should go to the emergency department if you have any of these signs of a more serious problem:
- You’re experiencing difficulty breathing.
- You have a fever above 100.4℉ for over 24 hours.
- You’re feeling confused or disoriented.
- You lose your appetite.
- You have pain in addition to itching.
- You have ulcers on your mouth or genitals.
- You have blisters on your skin.
- Take lukewarm showers and completely dry your skin.
- Wear loose-fitting clothes.
- Anti-itch lotion (Sarna) or hydrocortisone cream
- OTC antihistamine medications
- Stop any new products.
- Use only fragrance-free products on the skin.
- Avoid irritants (jewelry, etc) on the rash.
Additional treatment options
Your doctor will take a full medical history and physical exam. They may scrape your skin to look for fungus or scabies. They may also take a biopsy of the rash to figure out the cause.
They may recommend patch testing if it looks like you have contact dermatitis. The doctor places patches of allergens on your back for 48 hours. When you come back to the office, the doctor removes the patches to see if your skin reacted to any of the allergens.
Your doctor may recommend:
- Prescription topical steroids or antifungal cream.
- Oral or steroid injections.
- Prescription antihistamines.
- Immune-modulating medications for psoriasis.
- Lifestyle changes, including diet.
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