Skin Rash on the Body: Types of Skin Eruptions and Their Possible Causes

A rash is an area of irritated or swollen skin and at the same time a symptom of many different conditions, from contact dermatitis to infection. Many eruptions itch, redden, or hurt, and some produce blisters and areas of damaged skin. Understanding the elements is useful so you can describe more precisely to a doctor what you see in the mirror.

What a rash is and what elements of eruptions exist

A rash refers to pathological elements on the skin and mucous membranes that differ from normal skin in color, texture, and appearance. They are divided into primary elements, which appear on unchanged skin, and secondary elements, which arise in place of primary ones. Primary elements can be cavitary or non-cavitary, and it is their combination that creates the picture on which a doctor builds hypotheses.

Secondary elements include erosions, ulcers, scales, crusts, fissures, excoriations, scars, areas of hyperpigmentation and depigmentation, and lichenification. Lichenification occurs in chronic dermatoses with severe itching, more often in eczema and neurodermatitis.

Types of rash: macules, papules, vesicles, hemorrhagic rash

• A macule (spot) is a localized change in skin color: vascular, pigmented, or artificial. Roseola is a small spot 1–5 mm in size, pale pink or red, that does not rise above the skin and disappears on pressure.
• A papule, or nodule, is a non-cavitary element that resolves without a trace. Sizes are miliary 1–3 mm, lenticular 0.5–0.7 cm, nummular 1–3 cm. When merging, papules form a plaque more than 5 mm in diameter.
• A vesicle is a cavity up to 0.5 cm with serous or serosanguineous contents; after it ruptures, an erosion remains. A bulla is structured the same way but is larger than 0.5 cm; a pustule differs by its purulent contents.
• Hemorrhagic rash is bleeding into the skin due to destruction of vessels: dots and spots that do not disappear when the skin is stretched.
• A wheal is a pink element with a whitish center due to edema of the papillary dermis; it lasts from minutes to several hours, itches, and disappears without a trace.

Possible causes of rash on the body

A rash is a symptom, not a diagnosis. Causes include various medical problems, irritating substances, and allergies; certain genes increase the likelihood of eruptions. Contact dermatitis is a common type: redness, itching, and sometimes small bumps exactly where the skin came into contact with the irritant.

A rash may appear immediately or may develop over several days. Pityriasis rosea usually resolves on its own within a few months; its cause is unknown, possibly viral, and it is not transmitted from person to person. Flu-like symptoms may precede the rash — fatigue, sore throat, fever, headache. First, a single oval scaly patch 2–5 cm (more often on the chest, thigh, shoulder, or neck), and after 5–15 days, symmetrical small scaly spots on the chest and back, and in children on the face and head. Afterwards, darker or lighter areas remain, which usually even out over several months without scars.

Small and red rash on the body, neck, abdomen, and back

A rash may combine macules and papules. In pityriasis rosea, small scaly spots occur on the chest and back and appear symmetrically. On dark skin, the same elements look gray, dark brown, or black; on light skin, they look pink and red.

Photographs with names help only as landmarks: similar pictures are produced by different conditions, and a diagnosis is not made from an image on the internet.

How a doctor determines the cause of eruptions

Diagnosis is comprehensive. A history is taken: whether similar episodes occurred before and whether any relatives have suffered from them. A dermatologist works with skin problems.

Scaly spots occur in psoriasis and eczema, and a single round spot occurs in ringworm. Therefore, the question "what is this" is answered by an examination, not by comparison with someone else's photograph.

When a rash requires urgent medical attention

See a doctor for a severe rash, for a rash that does not go away, and for eruptions accompanied by other symptoms. A separate case is pregnancy: a new rash requires urgent contact with a doctor, since pityriasis rosea in the first 15 weeks is associated with a risk of miscarriage and preterm birth.

If the rash remains itchy after over-the-counter remedies or persists for more than three months, a conversation with a doctor is appropriate.

A rash by itself is not a reason to call an ambulance; 103/112 — if the rash is accompanied by a life-threatening condition. A new rash during pregnancy is a reason to contact a doctor urgently, but not necessarily to call an ambulance.

This material is for reference and does not replace a doctor's consultation: show the rash to a specialist, not to a search engine.

This content is for reference and does not replace a doctor's consultation. Medical disclaimer