What causes a leg rash?

Leg rashes can be caused by a wide variety of diseases and conditions, such as infection, inflammation, allergic reaction, parasite and insect bites, and autoimmune processes. For example, an acute leg rash that appears suddenly may be caused by an allergic reaction or sensitivity to a particular substance, such as poison ivy, hair waxing or shaving, or an insect bite.

A chronic, ongoing leg rash may be caused by atopic dermatitis (eczema) or psoriasis. Psoriasis is characterized by slightly raised patches of itchy skin with red borders and silver scales.

Serious causes of leg rashes include a severe allergic reaction with anaphylaxis (tightening and closing of the airways) and cellulitis (an invasive bacterial or fungal infection of the skin and surrounding tissues).

Infectious causes of a leg rash

A leg rash may be caused by an infection including:

  • Bacterial infection, such as from streptococcal and staphylococcal bacteria

  • Chickenpox (viral infection)

  • Fifth disease (mild viral infection in children that can also cause harm to unborn babies)

  • Folliculitis (infection or inflammation of a hair follicle)

  • Fungal infection of the skin (also called ringworm)

  • Measles (viral infection)

  • Rocky Mountain spotted fever

  • Viral infections such as roseola

Allergic causes of a leg rash

A leg rash may be caused by an allergic reaction including:

  • Allergic contact dermatitis, such as an allergy to a perfumed body lotion

  • Allergic purpura

  • Drug reaction

  • Eczema (atopic dermatitis), including chronic eczema

  • Irritant contact dermatitis, such as poison ivy, poison oak, or poison sumac

Autoimmune and inflammatory causes of a leg rash

A leg rash may be caused by autoimmune and inflammatory disorders including:

  • Cutaneous lupus (autoimmune disease that affects the skin)

  • Discoid eczema (often due to dry skin)

  • Erythema nodosum (inflammatory disorder)

  • Psoriasis

  • Vasculitis (inflammation of blood vessels)

Parasite or insect causes of a leg rash

A leg rash may be caused by parasites or insects including:

  • Bedbugs

  • Body lice

  • Fleas or ticks (ticks carry the bacteria that cause Rocky Mountain spotted fever)

  • Mites (parasites that cause scabies)

  • Mosquitoes (mosquitoes also carry parasitic diseases)

Other causes of a leg rash

A leg rash may also accompany the following conditions:

  • Anxiety and stress

  • Heat (heat rash)

  • Methamphetamine abuse

  • Varicose veins

  • Venous eczema (also called gravitational dermatitis; a complication of deep vein thrombosis or other blood vessel disorder)

Life-threatening causes of a leg rash

In some cases, a leg rash may accompany a serious or life-threatening condition, including a severe allergic reaction called anaphylaxis.  Life-threatening conditions include:

  • Anaphylaxis

  • Erythema multiforme (type of allergic reaction)

  • Toxic epidermal necrolysis (skin and mucosal loss due to a severe medication reaction)

What are the potential complications of a leg rash?

In some cases, a leg rash can lead to complications, especially if there is severe itching and scratching that leads to breakdown of the skin. Scratching can introduce bacteria or fungus in the layers of skin, resulting in infections. Complications include:

  • Bacterial or fungal infection of the skin

  • Cellulitis (an invasive bacterial or fungal infection of the skin and surrounding tissues)

  • Open sores and lesions

  • Permanent change in skin texture, scarring

  • Permanent skin discoloration

Complications of underlying causes of a leg rash, such as diabetes or peripheral artery disease, can also occur. You can best reduce the risk of complications of a leg rash and its underlying causes by following the treatment plan you and your health care provider develop specifically for you.

References:

  1. Rashes affecting the lower legs. DermNet NZ. http://dermnetnz.org/site-age-specific/lower-leg.html.
  2. Rash. Medline Plus, a service of the National Library of Medicine National Institutes of Health. http://www.nlm.nih.gov/medlineplus/ency/article/003220.htm.
  3. Skin rashes and other changes. FamilyDoctor.org. http://familydoctor.org/online/famdocen/home/tools/symptom/545.html.
  4. What Are Varicose Veins? National Heart Lung and Blood Institute Diseases and Conditions Index. National Institutes of Health. http://www.nhlbi.nih.gov/health/dci/Diseases/vv/vv_all.html.
  5. New itchy skin rashes in Adults. Skinsight. http://www.skinsight.com/diseaseGroups/itchyNewAdultSkinRashes.htm.
INTRODUCTION

What is a leg rash?

A leg rash is an inflammatory reaction of the skin on the legs that may extend to the feet. Leg rashes can be caused by a wide variety of mild to serious diseases, disorders and conditions. Leg rashes can affect a small to large area of one or both legs and can occur in all age groups and populations.

... Read more about leg rashintroduction

SYMPTOMS

What other symptoms might occur with a leg rash?

A leg rash can occur by itself or with other symptoms that affect the skin and possibly other areas of the body. Symptoms vary depending on the underlying disease, disorder or condition. For example, you may have flu-like symptoms if the leg rash is due to infection or inflammation. Some coexisting symptoms, such ... Read more about leg rashsymptoms

Medical Reviewer: Cynthia Haines, MD Last Annual Review Date: Aug 5, 2013 Copyright: © Copyright 2014 Health Grades, Inc. All rights reserved. May not be reproduced or reprinted without permission from Health Grades, Inc. Use of this information is governed by the HealthGrades User Agreement.

This Article is Filed Under: Skin, Hair and Nails


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