Why Is There an Itchy Rash on My Arms and Legs?

An itchy rash on the arms and legs is common and can be caused by numerous conditions. It can cause a serious disruption in normal day-to-day activities and make sleeping near impossible.

Pruritis is the medical term for itching. When an itchy rash develops on the arms or legs, the first step to treatment is identifying the cause. Once the cause is determined, then targeted treatment can begin.

Here we will cover many of the common causes of an itchy rash on the arms and legs, how to diagnose the rash and treatment options.

itchy woman scratching her arm

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Possible Causes

There are many possible causes for an itchy rash on the arms and legs. Here is information on each type of rash and what distinguishes it from other rashes.

Allergic Contact Dermatitis

Allergic contact dermatitis is an allergic response that happens after skin has come into contact with an allergen. There are numerous allergens that can cause an allergic reaction to the skin. Some of the most common are:

  • Nickel: Found in some jewelry
  • Latex: Ingredient in some rubber products
  • Paraphenylenediamine (PPDA): An ingredient in some permanent hair dye
  • Poison ivy: A low-lying plant found in many areas of the country
  • Fragrances: Perfumes added to cosmetics, shampoos, and lotions

An allergic contact dermatitis rash may not form until 24 to 48 hours after exposure. The rash can produce the following symptoms:

  • Redness
  • Swelling
  • Itchiness
  • Blisters
  • Flakiness

Learn more about allergic contact dermatitis.

How to Know If a Rash Is Allergic Contact Dermatitis

One of the best ways to determine if a rash on the arms or legs is allergic contact dermatitis is to look at the rash pattern. Does it follow a specific pattern to something that touched skin? For example, is there a mark from a watch, or does the rash follow along on the legs where grass or poison ivy grazed it? Contact a healthcare provider if there is no clear cause for the rash.

Flea Bites

Fleas are tiny bugs that feed on animal and human blood. A flea bite does not usually cause a serious rash.

The rash from a flea bite can cause the following rash symptoms:

  • Pain
  • Itchiness
  • Small raised bumps

If someone is allergic to a flea bite, the rash may be more significant with blistering and swelling.

One of the specific concerns that come with a flea bite is developing a fleaborne illness. Some fleas carry diseases that can cause serious conditions. Here are potential conditions that someone can develop after being bitten by a disease-carrying flea:

Fifth Disease

Fifth disease is a viral illness that is also known as parvovirus. It causes a characteristic red rash on the face that appears like a slap. It is most commonly seen in children.

There can also be a rash on the arms, legs, chest, and back. However, in healthy people, fifth disease tends to be a mild illness that resolves on its own. It is passed on from person to person through respiratory secretions like salvia from a cough or sneeze.

The symptoms of a fifth disease rash are:

  • Rash on the face, arms, or legs
  • Fever
  • Headache
  • Stuffy or runny nose
  • Itching

Learn more about parvovirus.

Allergic Eczema

Allergic eczema is a form of eczema that is caused by an allergen. An allergen is something that causes the immune system to activate and produces an allergic response. The allergen could be perfume, jewelry, cleaning product, or something else.

The itchy rash develops where the allergen touched the skin. Commonly on the arms and legs since those are usually uncovered and touch environmental surroundings.

The rash that allergic eczema creates has the following symptoms:

  • Itchiness
  • Swelling
  • Redness
  • Small bumps that can ooze when scratched
  • Scaly skin patches

Learn more about eczema.

Chickenpox

Chickenpox is a very contagious condition that causes an itchy red rash that can cover most of the body, including the arms and legs. Caused by the varicella-zoster virus, chickenpox was a common childhood illness until the vaccine became available in 1995.

The classic chickenpox rash is red and itchy. The rash will have blisters filled with fluid that eventually scab over. Other symptoms can include fever, fatigue, headache, and decreased appetite.

Cellulitis

Cellulitis is a bacterial infection of the deep layers of the skin. It can infect anywhere on the body but is commonly seen in the legs and feet.

Cellulitis can be caused by several different kinds of bacteria but the most common type is group A Streptococcus. The symptoms can come on quickly and spread fast. Antibiotics prescribed by a healthcare provider are necessary to treat cellulitis.

The symptoms of a cellulitis rash include:

  • Redness
  • Swelling
  • Pain
  • Itchiness
  • Rash that is warm to the touch
  • Pitted skin
  • Blisters

If left untreated, the infection can spread through the body causing more serious symptoms like a bloodstream infection.

Drug Allergy

A drug allergy is an immune response to a certain medication. The immune response can be small, only causing a rash, or the response can be significant, causing anaphylaxis, a life-threatening reaction that causes difficulty breathing and decreased blood pressure.

Any drug can cause an allergy but certain ones are more commonly seen:

  • Penicillin antibiotics
  • Sulfonamide antibiotics
  • Cephalosporins
  • Anticonvulsants
  • Aspirin
  • Nonsteroidal anti-inflammatory drugs (NSAIDs)

Symptoms of a drug allergy vary from hives (an itchy rash) and swelling to difficulty breathing. Whenever a drug allergy is suspected, it's important to contact a healthcare provider.

Measles

Measles is a highly contagious virus that starts seven to 14 days after exposure. The illness begins with a cough, fever, runny nose, and red watery eyes. Two to three days later small white spots (Koplik spots) begin to appear in the mouth. Then, three to five days after that the measles rash begins.

The measles rash typically starts on the face, along the hairline. It then moves down the face to the arms, body, and legs.

The rash appears with flat red spots. A person can have a very high fever with the rash, up to 104° Fahrenheit. The rash is usually not itchy, but the heat from a high fever can make someone itchy.

Hives

Hives, medically known as urticaria, is a red, itchy rash that can be caused by an allergy, viral infection, stress, or outdoor conditions. The rash can happen on any part of the body but is generally seen on the arms and legs.

One of the main characteristics of a hives rash is how it can come and go, sometimes very fast. Other traits of a hives rash are:

  • Raised red welts with pale centers
  • Itchiness
  • Swelling

Hives usually go away in 24 to 48 hours.

Other

There are so many different causes of itchy rashes on the arms and legs. The above list of causes is extensive but not exhaustive. Here are a few other potential causes of itchy rashes:

When to See a Healthcare Provider

Rashes can be caused by many different conditions. It's important to know when a rash is serious and needs to be assessed by a healthcare provider. Talk to a healthcare provider if a rash follows any of these patterns:

  • Covers the body
  • Comes on suddenly
  • Spreads quickly

Also, it's time to see a healthcare provider if the following symptoms happen with a rash:

Diagnosis

A healthcare provider will be able to diagnose a rash largely based on its appearance and health history.

If a healthcare provider cannot determine the cause based on their evaluation, they may order additional testing. Patch testing is one diagnostic tool used to diagnose some allergies. It is a helpful test when a rash is likely caused by an unknown allergen.

Blood testing is also another tool used to diagnose rashes that may have caused a blood infection, changes in antibodies, or have been caused by an allergy.

Another way a healthcare provider can diagnose a rash is with a KOH test. A KOH is done by scraping a small amount of skin and placing it under a microscope to look for an infection. It is a painless procedure.

Treatment

Treatment for an itchy rash on the arms and legs will depend upon the cause of the rash. One of the first steps to treating the rash is to remove the cause if possible. Once the cause is removed, here are other treatment options:

  • Avoid triggers: Once the cause of the rash is found, it's important to avoid it. Triggers could be foods, animals, pollen, fragrances, and so much more.
  • Moisturizers: Itchy rashes can often benefit from moisture. Fragrance-free lotions and creams can seal in moisture and reduce itching.
  • Home remedies: There are several ways you can manage the symptoms of an itchy rash at home. An oatmeal bath or cold compress can alleviate the itch.
  • Prescription medication: Certain rashes need prescription medication to clear up. Always follow a healthcare provider's directions on how to use the medication for the best results.
  • Over-the-counter (OTC) medication: OTC medications can be a good choice for mild rashes. Advil (ibuprofen) can reduce pain and swelling. Hydrocortisone cream and calamine lotion are good for relieving itching, and an antihistamine is helpful for itching, redness, and swelling.

Always be sure to check with a pharmacist or healthcare provider before starting a new medication.

Summary

An itchy rash on the arms and legs can cause work, life, and sleep disruptions. There are many different rash causes, from a drug allergy to poison ivy. Finding out what is causing the rash is the first step toward getting better.

Once the underlying cause of the rash is found, treatment can be geared for that specific cause. Treatment can usually be done from home; however, if it does not get better or worsens, it's time to talk to a healthcare provider for further guidance.

A Word From Verywell

A rash can be a sign of a mild or serious condition. A simple rash can become infected and lead to much bigger problems. Anytime you question what to do for a rash, you should talk to your healthcare provider.

Even general healthcare providers may find it hard to diagnose the rash and will refer you to a dermatologist. Following their directions is important to stop the itch and prevent the rash from worsening.

Frequently Asked Questions

  • How can you tell if a rash is serious?

    A more serious rash is one that comes on quickly, spreads rapidly, and covers most of the body. It is a medical emergency if there is any difficulty breathing as it could be a sign of anaphylaxis. Always refer to a healthcare provider to determine the seriousness of a rash.

  • Can anxiety cause an itchy rash?

    Anxiety and stress can cause an itchy rash called hives (urticaria). Hives are itchy red bumps that can show up on any part of the body. This kind of rash can be caused by other things as well.

  • How do I get rid of a rash on my arms and legs?

    The first step in getting rid of a rash on the arms and legs is to find out what caused it. If you can, remove whatever it is that caused the rash. Then treatment should focus on that underlying cause. In some cases, home treatment with lotion, hydrocortisone cream, or an antihistamine can do the trick. For more serious rashes, a healthcare provider will need to evaluate the rash to determine the right treatment.

17 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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  2. Johns Hopkins Medicine. Fleas, mites, and chiggers.

  3. Centers for Disease Control and Prevention. Fleaborne disease in the United States.

  4. Centers for Disease Control and Prevention. Parvovirus B19 and fifth disease.

  5. Johns Hopkins Medicine. Eczema.

  6. Centers for Disease Control and Prevention. Chickenpox (varicella).

  7. Centers for Disease Control and Prevention. Cellulitis: all you need to know.

  8. American College of Allergy, Asthma, & Immunology. Drug allergies.

  9. Centers for Disease Control and Prevention. Measles (rubeola).

  10. Kanani A, Betschel SD, Warrington R. Urticaria and angioedemaAllergy Asthma Clin Immunol. 2018;14(2):59. doi:10.1186/s13223-018-0288-z

  11. American Academy of Dermatology Association. Rash 101 in adults.

  12. Fischer D, Vander Leek TK, Ellis AK, Kim H. AnaphylaxisAllergy Asthma Clin Immunol. 2018;14(2):54. doi:10.1186/s13223-018-0283-4

  13. MedlinePlus. Rash evaluation.

  14. MedlinePlus. Skin lesion KOH exam.

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By Patty Weasler, RN, BSN
Patty is a registered nurse with over a decade of experience in pediatric critical care. Her passion is writing health and wellness content that anyone can understand and use.