Skin Rashes

1 Skin Rashes Summary

Skin rash refers to an inflammation of the skin that leads to a change in the color or texture. It is not a specific diagnosis as such and inflammation may be caused by multiple factors.

Most of the rashes are harmless and do not require any specific treatment. Some rashes, like dark red or purple rashes, need immediate medical attention. These rashes may be associated with potentially life-threatening conditions like meningitis and septicemia.

Some of the warning symptoms that warrant a doctor’s visit are:

  • Persistent rashes
  • Feeling unwell
  • Rash does not fade when pressure is applied in the region
  • Unexplained onset of rash

Skin rashes are described in different ways, including:

  • Erythema – redness of skin
  • Macules – flat and unusually colored skin regions. The color may be red, purple, brown or white.
  • Papules – small raised skin surfaces that are half a centimeter in diameter
  • Nodules – raised skin surfaces that are larger than half a centimeter
  • Plaques – reddish, raised skin surfaces
  • Scales – raised skin surface with flaky, silvery-white appearance
  • Purpura – red or purple lesions on the skin that do not fade with pressure. These are two types:
    • Petechiae – smaller in size with <1 cm diameter
    • Ecchymoses – larger than petechiae with diameter >1 cm
  • Blisters – skin swelling that is filled with liquid. Vesicles refer to small blisters that are <1cm in diameter, while larger ones are known as a bulla. Blisters filled with pus are called as pustules.

There are multiple reasons for the inflammation of the skin. Erythema may be caused by cellulitis, utricaria, burns, viral infections, rheumatoid arthritis, hyperthyroidism, and autoimmune conditions like systemic lupus erythematosus.

Scaly erythema results from psoriasis, eczema, seborrheic dermatitis, athlete’s foot, pityriasis rosea, lupus erythematosus and lichen planus. Macules may be caused by certain medications, viral infections, melanoma, vitiligo, and pityriasis versicolor.

A dark red or purple macule that does not fade when pressure is applied to the skin, may be caused by meningitis or blood infection. Acne, wart, seborrheic wart, scabies, insect bites, and skin tags are the common causes of papules.

Psoriasis may also lead to papules. Purpura or petechiae may result from meningococcal infection. Injury to skin and liver diseases like cirrhosis may also lead to purpura.

Some of the less common causes of purpura and petechiae are vasculitis and low level of platelets in the blood. Skin cancer, lipoma, and sebaceous cyst are implicated in the development of nodules. Other causes are rheumatoid nodules and Heberden's nodes.

Causes of blisters are many, including contact dermatitis, eczema, immune system diseases, viral infections, and skin infections. Viral or bacterial skin infection, inflammation, acne, and rosacea lead to pustules on skin.

During the diagnosis of a rash, the primary feature of the rash is noted, followed by other characteristics. Observations on the distribution of the rashes provide indications on the probable cause of the rash.

Further tests and investigations are based on the underlying cause of the rash. Rashes are often treated by treating the condition that leads to skin inflammation.

Non-prescription medications like anti-itch creams, oral antihistamines, moisturizing lotions and antifungal medications are used to treat rashes. When rashes persist, medical advice is suggested.

2 Causes

There are different types of rashes, each with a different cause.

Non-scaly, red erythema is caused by:

  • Cellulitis, a type of skin infection
  • Utricaria, an allergic reaction
  • Certain medications
  • Burns
  • Viral infections like measles and rubella
  • Vasculitis, a condition characterized by inflammation of blood vessels
  • Erythema nodosum, a condition in which reddish nodules appear in the shins
  • Hyperthyroidism, a thyroid disorder caused by overactive thyroid glands
  • Systemic lupus erythematosus, and inflammatory condition

Scaly, red erythema is caused by: 

  • Psoriasis – a condition characterized by inflammation of skin
  • Eczema – or dermatitis, this condition is also characterized by inflammation of the skin. Seborrhoeic dermatitis is another type of dermatitis, also known as seborrheic eczema.
  • Fungal infections – many fungal infections like athlete’s foot, tinea cruris infection, ringworm, and candida infection lead to scaly, red rashes.
  • Pityriasis versicolor – a skin condition caused by yeast-like organism
  • Lupus erythematosus – an inflammatory skin condition
  • Lichen planus – a condition that causes itchy rashes on skin

Macules are caused by:

  • Certain medications cause red-colored macules. Rashes caused by viral infections like measles and rubella are reddish.
  • Melanoma may result in brown colored macules, and these may change its color and size.
  • Vitiligo causes white macules, while pityriasis versicolor cause flaky, discolored areas with macules
  • Meningitis and septicemia are two serious conditions that result in dark red or purple-colored macules.

A common cause of papules is acne wart, seborrheic wart, scabies, insect bites, and skin tags. Psoriasis also may result in the formation of papules.

Purpura and petechiae are dark-colored and do not fade with pressure. These are called by meningococcal infection. Skin injury, repeated coughing and liver diseases like cirrhosis result in purpura.

Idiopathic thrombocytopenia purpura is a less common cause of the skin rash.

Nodules are caused by a sebaceous cyst, lipoma, skin cancer, and wart. Rheumatoid nodules and Heberden's nodes are also implicated in the formation of nodules on the skin.

Some common causes of blisters are:

  • Inflammatory skin conditions like contact dermatitis and eczema.
  • Immune system diseases like bullous pemphigoid.
  • Viral infections including chicken pox and foot and mouth disease.
  • Herpes simplex and herpes zoster infections

Pustules are caused by: 

  • Viral skin infections like cold sores caused by herpes simplex virus
  • Psoriasis
  • Skin reaction to certain medications
  • Acne and rosacea that cause pustules on face

Ulcers on the skin are caused by venous leg ulcers, pressure ulcers, diabetes skin ulcers, or malignant skin ulcers.

A number of skin conditions result in itching. Dry skin, eczema, contact dermatitis, urticaria, lichen planus, psoriasis, and folliculitis are some of the conditions that cause itchy skin.

In children, rashes may be caused by chickenpox, measles, scarlet fever, fifth disease, Kawasaki disease, impetigo and viral infection like a hand, foot, and mouth disease.

Chickenpox results in red, itchy blisters on the skin. Widespread itchy, red rashes are caused by measles. Sand-paper rashes are caused by streptococcus infection.

Kawasaki disease is a rare condition that results in fever and rashes in young children. Impetigo is a contagious bacterial infection with itchy rashes on face, neck, and hands.

3 Diagnosis and Treatment

Rashes refer to inflammation of the skin and may be caused by multiple factors. The first step in the diagnosis of a rash is the physical examination, wherein the primary feature of the rash is noted.

It is then described on the basis of this feature like circular, linear, or ring-shaped. Other characteristics of rashes are then observed. This includes density, color, size, consistency, shape, tenderness, and temperature.

The doctor may also ask about diet, recent changes in products or medications, and hygiene. Distribution of the rashes on the body provides an important clue to the most probable cause of the rashes.

These facts on rashes are then used in the differential diagnosis of the cause. Skin tests are sometimes suggested, as in the case of atopic eczema. Other tests and investigations are based on the suspected underlying condition.

Skin biopsy helps in the diagnosis of many conditions including granuloma annular and lichen planus. Blood and skin tests help in the identification of many causes. Allergy test and complete blood count are also commonly used in the confirmatory diagnosis of skin rashes.

Treatment of rashes depends on the underlying cause of the symptom. One of the first methods to be used to treat rashes is to try home remedies for soothing rashes. If a known allergy is the cause of skin rashes, try to avoid exposure to the trigger as much as possible. Doctor’s advice is needed if the rashes are persistent.

Some of the common preventive measures for rashes are: 

  • Using mild cleansers instead of strong, scented bars
  • Wash hair and skin with warm water to avoid dry skin
  • Avoid covering the rash with clothes or cotton
  • Avoid using new cosmetics
  • Avoid scratching the skin with rash

Over-the-counter hydrocortisone cream may help in easing the discomfort due to rashes. Calamine lotion is also useful in relieving rashes. For pain associated with rashes, acetaminophen and ibuprofen can be used.

Antibiotics are the preferred treatment method for a bacterial infection that results in rashes. Stopping medications that cause rashes help in relieving the symptom. Topical steroids are used to reduce the skin inflammation.

Oral antihistamines are also suggested in treating inflammation. The dose of antihistamines may be increased if the usual dose does not give much relief. Antifungal medications like clotrimazole and terbinafine are used in case of fungal infections.

For many infections, prescription-strength medications like mupirocin are suggested. Rashes caused by pityriasis rosea heal with exposure to sunlight. Exposure to the sun for 6-12 weeks helps to resolve the condition.

Freezing the lesions or injecting steroids into the rashes helps to alleviate rashes in the case of granuloma annular. Over-the-counter creams, lotions, and ointments are used to control itching and swelling caused by eczema.

In severe cases of eczema, cortisone pills and shots are recommended. Phototherapy also may be useful in reducing the symptom in case of eczema. In severe cases, ultraviolet (UV) A or UVB from special lamps are used to treat the condition.

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