Thigh Rash: Causes

What causes thigh rash?

Thigh rash may have many possible causes, including allergens (agents that cause allergies), infections, autoimmune disorders, or other causes such as stress.

Allergic or inflammatory causes of thigh rash

Thigh rash may be caused by contact dermatitis. Common triggers include:

• Cosmetics, dyes or detergents
• Industrial chemicals, such as those found in elastic, latex and rubber
• Metallic substances (various metals, copper, wire)
• Poison ivy or oak

Other allergic or inflammatory causes of thigh rash include:

• Eczema (skin disorder causing scaly or blistering rashes that may be caused by allergy)
• Food allergies (allergic reactions to certain foods)
• Insect bite allergy such as a bee sting
• Intertrigo (irritation caused by rubbing together of skin surfaces)

Infectious causes of thigh rash

Thigh rash can also be caused by infections including:

• Chickenpox or shingles
• Eczema (skin disorder causing scaly or blistering rashes that may be caused by infection)
• Erythema nodosum (red nodules under the skin associated with fever and other symptoms)
• Impetigo
• Lyme disease (inflammatory bacterial disease spread by tick bites)
• Measles, mumps, rubella, roseola, and scarlet fever
• Meningitis (infection or inflammation of the sac around the brain and spinal cord)
• Pityriasis rosea (rash resembling the shape of a pine tree)
• Ringworm
• Rocky Mountain spotted fever
• Strep throat (bacterial throat infection)

Autoimmune causes of thigh rash

Thigh rash can also be caused by autoimmune disorders including:

• Kawasaki disease (rare, serious pediatric disorder characterized by inflammation of blood vessels, high fever, rash, and mucous membrane changes)
• Psoriasis
• Rheumatoid arthritis (chronic autoimmune disease characterized by joint inflammation)
• Systemic lupus erythematosus (disorder in which the body attacks its own healthy cells and tissues)

Other causes of thigh rash

Thigh rash can be caused by other factors including:

• Extreme cold or heat
• Medications
• Stress

Serious or life-threatening causes of thigh rash

In some cases, rash may be a symptom of a serious or life-threatening condition that should be immediately evaluated in an emergency setting. These include:

• Allergic purpura
• Anaphylaxis (life-threatening allergic reaction)

Questions for diagnosing the cause of thigh rash

To diagnose your condition, your doctor or licensed health care practitioner will ask you several questions related to your rash including:

• When did the rash begin?
• Are you taking any medications?
• Do you have any known allergies?
• Does the rash cause any itching or scaling?
• Do you feel otherwise healthy?
• Have you tried any new products recently, such as soaps, perfumes or sprays?
• Have you spent a lot of time outdoors lately?

What are the potential complications of thigh rash?

Because thigh rash may be due to serious diseases, failure to seek treatment can result in serious complications and permanent damage. For example, infectious diseases, such as mumps or measles can lead to rare but serious complications, including miscarriage, hearing loss, and serious brain infections, such as encephalitis or meningitis.

Once the underlying cause of your rash is diagnosed, it is important for you to follow the treatment plan that you and your health care professional design specifically for you to reduce the risk of potential complications including:

• Arthritis
• Cellulitis (infection of the skin)
• Cognitive difficulties
• Encephalitis (inflammation of the brain)
• Meningitis (infection of the protective covering of your spinal cord)
• Miscarriage or stillbirth
• Paralysis
• Permanent hearing loss
• Secondary infections, which may develop from scratching and related skin trauma

References:

Skin rashes and other changes. FamilyDoctor.org. http://familydoctor.org/online/famdocen/home/tools/symptom/545.html. Accessed April 20, 2011.

Rashes. Medline Plus, a service of the National Library of Medicine National Institutes of Health. http://www.nlm.nih.gov/medlineplus/ency/article/003220.htm. Accessed April 20, 2011.