10 most common causes
Why is your skin itchy?
Itching, also known as “pruritus,” is a common symptom that everyone will experience at some point. Itching occurs when itch-specific nerves in your skin are stimulated and then transmit this information through the spinal cord to your brain.
Some conditions can cause the whole body to itch, while others only affect certain areas, like the arms.
1. Dry skin
- Flakey or scaly looking skin
Dry skin is the most common cause of itchy upper arms. It is most common in older people. It can be caused by frequent bathing, using soaps that strip the skin of moisture, and during winter months when indoor heat is frequently used.
Dry skin is easily treated by regular use of a moisturizer, which is especially important during the winter.
2. Eczema (atopic dermatitis)
- Intense itching
- Red, scaly rashes
- Thickened-appearing skin
Atopic dermatitis, or eczema, is a type of rash that is often seen in people who have other allergic diseases, like asthma or food allergies. In some people, it can be caused by a gene that weakens the skin’s natural barrier, which allows it to be more susceptible to allergens and irritants. The hallmark of eczema is itching, which can often make the rash even worse.
Treatment is based on how severe it is. The main therapy is frequent use of thick moisturizers, along with using fragrance-free, hypoallergenic skin care products. Topical steroid creams can help clear up inflamed areas; these come in many different strengths and need a prescription. An allergist or a dermatologist may also recommend other specialized medications if your eczema is very severe.
Science is trying to learn more about the way the immune system plays a role in itching. Certain chemicals have been identified that cause itching to occur. One of these chemicals, called interleukin-31, is being studied as the target of a drug to help people who suffer from diseases like atopic dermatitis. —Dr. Amrita Khokhar
- Red, sharply-defined rashes
- Silvery-appearing scaliness on the skin
Psoriasis in an inflammatory skin disease that leads to red, scaly rashes. It can affect different parts of the body. The outside of the elbow and the surrounding area is a common location. People who have psoriasis are at risk for other diseases, like psoriatic arthritis, which can lead to joint pain and stiffness throughout the body.
There are many treatments for psoriasis. Mild rashes can be treated with a topical steroid cream. Another effective treatment is phototherapy, which is ultraviolet light exposure performed under the supervision of a dermatologist. Finally, there are many types of oral medications or injectable medications available that work by blocking parts of the immune system response that leads to inflammation.
4. Allergic contact dermatitis
- Intense itching
- Red rash
- In severe cases, blistering can occur
Allergic contact dermatitis is an allergic reaction that occurs after your skin comes into contact with an allergen (a substance that triggers this reaction). Allergic contact dermatitis can be caused by many different allergens, but the most common ones that could affect the upper arms include fragrances, dyes used in clothing, and preservatives found in skin care products. Certain plants, like poison ivy, contain oils that also elicit an allergic reaction if you happen to brush up against them with bare skin.
An allergist or dermatologist can help you figure out if your rash is from allergic contact dermatitis. If it seems likely, patch testing can help pinpoint the cause. Treatment requires avoiding the allergen and using topical steroids for a short period of time to treat the rash.
5. Ringworm (tinea corporis)
- Circular red rash that spreads outwards
- Center of rash appears better than the surrounding area
- The border of the rash is raised
Ringworm is caused by a fungus—not an actual worm—on the surface of the skin. There are a few different types of fungi, also called dermatophytes, that can cause it. Ringworm is very contagious and you can become infected after touching someone who has it, a contaminated surface, or an animal who has the disease.
Ringworm can usually be treated with a topical antifungal cream that you can get over-the-counter or by prescription.
You should ask if the specific condition causing your upper arm to be itchy will go away with treatment, as with something like ringworm. Or is it something more persistent, like eczema or psoriasis. This will give you a better idea of what to expect in terms of treatment and progress. —Dr. Khokhar
6. Insect bites
- Raised welts where the bite occurred
Insect bites, especially those from mosquitoes and blackflies, can lead to intensely itchy rashes and bumps. Mosquitoes and blackflies will bite unclothed skin, which is why the arms are so frequently affected.
While there’s no treatment after you’ve been bitten, you can do certain things to try to prevent being bitten. This includes wearing long sleeves and long pants, using an insect repellent like DEET or picaridin, and avoiding going out at dawn and dusk when insects are the most active.
- Pus-filled red bumps around hair follicles
Folliculitis is an infection of the hair follicles, usually by a bacteria called Staphylococcus aureus. This leads to red, sometimes pus-filled bumps on the arms (or other parts of the body) which can be itchy.
Topical antibiotics, like mupirocin, can often clear up folliculitis. But if your rash isn’t improving with topical medication, an oral antibiotic might be prescribed.
8. Urticaria (Hives)
- Raised, swollen, and irregularly shaped welts on the skin
- Intense itching
Hives are often the result of an allergic reaction, such as a food allergy, medication allergy, or bee sting. Sometimes, hives can occur spontaneously, which means there’s no apparent cause for them. While they often only last a few hours before disappearing, hives can be intensely itchy and disruptive.
Hives often respond quickly to antihistamines, a type of oral allergy medication. Identifying and avoiding the suspected allergen is also important.
9. Brachioradial pruritus
- Itching of the outer arms
Brachioradial pruritus causes itching of the arms, and is thought to be caused by a nerve injury in the cervical spine. It also occurs in people who get a lot of sun exposure. It can worsen during the summer months.
Brachioradial pruritus isn’t well understood, so it’s not clear what the best treatment is, but some people find relief by using prescription topical itch creams.
10. Polymorphous light eruption
- Red, itchy rash in sun-exposed areas
Polymorphous light eruption (PMLE) is an itchy rash that occurs in response to sun exposure, often hours or days afterwards. It’s due to exposure to the ultraviolet radiation found in sunlight. It most frequently affects fair-skinned women in their 20s and 30s, usually during the spring and summer months.
PMLE can be prevented by avoiding the sun. Wearing long-sleeved tops or using sunscreen can also help. If you get the rash, prescription topical steroids can help heal it quickly, and over-the-counter antihistamines can help relieve the itch.
Other possible causes
Some less common causes of upper arm itching include the following:
- Polycythemia vera: This is a blood disorder where excess amounts of red blood cells are produced by the body. The increase in red blood cells can cause itching, often of the arms.
- Dermatomyositis: This is an autoimmune condition that causes inflammation in the muscles and can also be associated with a purple-colored, itchy rash that can affect the arms, as well as the face, hands, and chest.
You should tell your doctor how long your upper arm has been itchy and if you’ve noticed itching or a rash anywhere else on your body. These two questions can really help pinpoint the possible causes. —Dr. Khokhar
When to see a doctor
You should see your doctor for upper arm itching if you notice the following:
- You have a rash that isn’t getting better or is worsening
- The itch is interfering with day-to-day activities
Treatments for itchy upper arms
Depending on the cause, some at-home remedies might relieve itchiness on your upper arm. These include:
- Applying moisturizing creams to the affected areas for dryness and eczema.
- Over-the-counter steroid creams, like hydrocortisone, for milder forms of allergic contact dermatitis.
- Taking an antihistamine for itchiness from insect bites.
Other treatments you might have:
Depending on the cause of your itchy upper arm, the following are some prescription medications that your doctor might prescribe:
- Steroid creams
- Oral steroids
- Immunosuppressant medications
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