What causes a rash on the legs? Related conditions and treatments

Overview: What does a rash on the legs look like?

So you think you have a rash on your leg? If you do, then you likely have noticed lesions on the leg. They may have various colors (red, purple, white, brown, and silver), but usually, they are red bumps, and the surrounding skin may be scaly or flaky. The lesions may be flat or raised. They may affect a small area or the entire leg. Fluid-filled blisters may be present that may eventually start oozing. Additionally, itchiness may accompany the scaly patches on the leg. Peeling of the skin may be another symptom of a leg rash that may cause cracks in the skin that may be painful.

Rashes to the body are quite common, but when they involve the legs, they're typically from an inflammatory skin condition called dermatitis. If you are suspicious of a rash on your legs, you should contact your dermatologist for further evaluation and treatment options. Of course, if you are given a prescription to treat the leg rash, make sure you check out SingleCare for prescription savings.

What causes a rash on the legs?

• Autoimmune or inflammatory skin diseases are typically the most common causes of a rash on the legs. Some skin conditions responsible are:

  • Dermatitis (contact dermatitis or atopic dermatitis)

  • Psoriasis 

  • Xeroderma (dry skin)

  • Lupus

  • Vasculitis

• A rash on the leg may also be caused by skin infections (bacterial, fungal, viral). Examples include:

  • Ringworm

  • Cellulitis

  • Folliculitis

  • Chickenpox

  • Shingles

  • Measles

  • Roseola

  • Lyme disease

• Various allergens may also cause a rash on the legs. Common allergens to be aware of are:

  • Insect bites (bee stings, mosquitos, fleas, ticks)

  • Medications (topical and oral)

  • Latex

  • Soaps

  • Detergents

  • Shampoos

  • Dyes

  • Pest infestations (lice, mites, scabies)

  • Poison ivy

  • Poison oak

  • Heat

• Other causes that may not be as common as previously discussed conditions may also be responsible for a leg rash. Examples include:

  • Poor circulation

  • Blood clot

  • Ulcer

  • Scars

  • Burns

  • Cancer

  • Anaphylaxis

  • Stress

Should I be worried about a rash on the legs?

A rash on the leg can happen and is not an uncommon condition. Typically a rash on the leg does not require immediate medical attention and can be managed at home with home remedies or OTC medications. Of course, there are some situations when a medical professional may be needed to diagnose the cause of the rash and give the appropriate treatment.

If you have a history of deep vein thrombosis, cancer, or severe allergic reactions, consult your healthcare provider about your rash. It may require comprehensive management rather than resolving on its own. Also, if the rash is rapidly spreading or you have fever, chills, nausea, or vomiting associated with the rash, you will need to seek medication attention immediately.

A rash on the leg does pose some complications to be aware of. If the rash itches, there is a strong possibility that the area will be scratched. This may cause bleeding and open sores to the skin (i.e. ulcers). These open wounds may take several weeks to months to heal and may cause significant pain in the area. This open skin may also allow bacteria and fungi inside the skin, causing an infection. Particularly with bacterial infections, the skin may become red, hot, and swollen, and even pus can accumulate, causing a systemic response such as fever, chills, or swelling to the leg. If a persistent fever, pain, and redness to the leg spreads, you should go to the emergency department. 

As mentioned, a rash on the leg can lead to ulcers. These open wounds, when healed, may leave scarring and discoloration on the leg. Occasionally the scarring and discoloration may be permanent. Lastly, if a rash on the leg is cancerous and not detected immediately, the cancer can spread. More aggressive treatments (i.e., surgical excision, chemotherapy, radiation) may be required to treat the cancer if left alone and untreated. Other serious causes of rashes, such as blood clots and anaphylaxis, need to be treated immediately, as in incidents, these conditions can be life-threatening. You can see your general practitioner or podiatrist if there are any questionable lesions on the legs that are not improving with standard treatments. Sometimes if the condition is more complicated, a dermatology specialist or oncologist will be required depending on the cause of the rash.

How is the cause of a rash on the legs diagnosed?

Now that you have decided to see a specialist for your leg rash, they will get a thorough medical history from you. They may ask if there is any personal or family history of cancer, poor circulation, or blood clots. Also, they will ask how long the rash has been there, whether it has gotten larger, changed color, bleeds, or is painful. The doctor may want to know if other rashes exist in another part of the body. Any change in medications, detergents, soaps, or cosmetics may also be reviewed. Additional questions may cover recent inflammatory or autoimmune flare-ups, medical conditions, and recent travel. The doctor will also want to know if you have tried any treatments on your own that have helped or made things worse.

Once the doctor has obtained your complete history, they will do a physical examination. During the exam, measurements and pictures will likely be taken. If the leg rash is concerning or traditional treatments are ineffective, they may consider a skin biopsy or running appropriate laboratory tests. Typically, this is not required, and a proper history and physical is usually enough for them to determine a diagnosis and provide treatment options. More aggressive diagnostic tools can be used if you have not been responsive. Once they have determined the cause of the rash on the leg, it will be easier to treat the condition.

Is a rash on the legs contagious? 

Occasionally, a leg skin rash can be contagious when the cause is infectious. Viral infections can be highly contagious, especially in children or immunocompromised children, as their immune systems are weaker and may not be able to fight the infection. Fungal infections of the lower legs or pest infestations can be spread using contaminated items such as towels, clothes, or sharing bedding. It is important to practice good hygiene and isolate when possible, especially if it is known that the rash is contagious. This will stop the spread to others.

How long does a rash on the legs last?

With appropriate treatment, most rashes should improve in 2-4 weeks. If the rash is due to underlying medical conditions, it may not improve until it is properly addressed.

How to stop a rash on the legs

Skin reactions on the leg that are due to an allergic reaction will typically improve on their own if the allergen can be avoided. Common skin conditions that involve itchy skin on the legs are typically from heat from the sun, new soaps, dyes in clothes, detergents, and perfumes. If this can be narrowed down to the cause, it can be avoided, and the rash will disappear.

For leg rashes caused by eczema or psoriasis, use antihistamines or steroid cream as advised. Most of these things can be found OTC, but your healthcare provider can provide stronger options. This treatment will usually allow the rash to improve within a month.

Treatment for a leg rash stemming from underlying medical conditions such as blood vessel issues, cancer, or anaphylaxis necessitates managing the root cause to improve the skin condition. This may take several months to years to improve.

Living with a rash on the legs

Luckily, there are many treatments to improve any red rash on the leg. In fact, you can find some things at home. Some natural remedies include oatmeal baths, aloe vera, tea tree oil, coconut oil, and cold compresses. If this does not help or you know your leg urticaria (hives) may be from a skin condition such as eczema, you may require some OTC treatments like hydrocortisone cream, skin moisturizers or ointments, calamine lotion, and sometimes Ibuprofen may be helpful when there is pain.

What’s next? Additional resources for people with a rash on the legs

Test and diagnostics

• Lyme disease: Diagnosis and Testing, Center of Disease and Prevention Control (CDC)

• Leg rash, American Family Physician

Scientific studies and clinical trials

• Lower extremity swelling and rash, Clinical Advisor

• Lower extremity shingles complicated by varicella zoster viral meningitis, American Journal of Medical Case Reports