Ringworm isn’t caused by a worm or parasite, despite its name. Instead, it’s a fungal infection that can affect various parts of the body such as the hands, feet, scalp, and groin. Conditions like athlete’s foot or jock itch are forms of the same fungus, known as tinea.

A typical ringworm rash appears as a flat, circular patch that grows in size over time. It usually features a red, raised border, which gives it the characteristic "ring" appearance. The rash may be itchy and scaly, and the skin in the center of the ring may eventually return to a normal tone.

Many healthcare providers can diagnose ringworm by examining the rash visually. However, testing might be required to rule out other skin conditions with similar symptoms.

Granuloma Annulare

Granuloma annulare is a long-term skin condition that presents with a round rash surrounded by a red border, often resembling ringworm. It typically appears on the hands and feet, affecting both sides of the body, and may be dark red or yellow in color.

The exact cause remains unclear, but it often follows a skin injury. Individuals with diabetes, HIV, or thyroid disorders may have a higher risk of developing it. Diagnosis is often visual, but a skin biopsy may be performed for confirmation.

Nummular Eczema

Nummular eczema is a type of inflammatory skin condition under the broader eczema category. It causes round, coin-shaped patches primarily on the arms, legs, hands, and torso. These patches can be itchy and scaly, similar to ringworm.

However, nummular eczema tends to be more inflamed and irritated, and the patches may ooze or crust. Dermatologists typically diagnose it visually but can confirm through a microscopic examination of skin samples if necessary.

Contact Dermatitis

Contact dermatitis results from an allergic reaction to substances like soap, makeup, certain fabrics, or poison ivy. The rash is itchy and scaly like ringworm but does not necessarily form a circular shape.

It may present with swelling, blisters, or heat, which are uncommon in ringworm. Diagnosis can be challenging without knowing recent exposure history, but allergy tests can confirm the cause.

Pityriasis Rosea

Pityriasis rosea is a non-serious skin condition with no definitive cause, though some believe it might be linked to herpes virus history. It often begins with a herald patch, a scaly round or oval lesion with a raised edge.

While this herald patch may resemble ringworm, pityriasis rosea usually progresses with additional symptoms like flu-like illness and the development of more skin lesions. The condition generally resolves on its own within eight weeks.

Lyme Disease

Lyme disease is a bacterial infection transmitted by ticks. Most individuals develop a rash within days or weeks of a bite. This rash, called erythema migrans, can resemble a ringworm rash with its expanding red ring appearance.

However, not everyone gets this rash, and it may vary in shape. Lyme disease is also associated with flu-like symptoms, unlike ringworm. Blood tests can detect antibodies to confirm the diagnosis.

Psoriasis

Psoriasis is an autoimmune condition that causes raised, thick, scaly skin plaques. Some types, such as plaque psoriasis and inverse psoriasis, can resemble ringworm due to their red, round patches.

Unlike ringworm, psoriasis plaques are typically elevated and may have silvery scaling. Inverse psoriasis appears as smooth, red patches. Diagnosis involves a medical history review and physical exam, with a biopsy if needed.

Seborrheic Dermatitis

Seborrheic dermatitis is an inflammatory condition that causes itchy, flaky rashes, commonly on the scalp, face, and groin. A subtype, petaloid seborrheic dermatitis, may form circular, ring-like lesions.

This condition is most common in adults aged 30 to 60 and may be triggered by stress or hormonal changes. A provider may diagnose it through visual examination or a skin biopsy.

When to Contact a Healthcare Provider

Even though a rash might not seem serious, it should be evaluated if it doesn’t improve within a couple of days. Rashes can spread, lead to other infections, or indicate an underlying issue.

Seek medical attention if your rash:

  • Covers a large portion of the body or spreads rapidly

  • Develops blisters or open sores

  • Comes with signs of an allergic reaction, like difficulty breathing or a swollen tongue

  • Causes pain or a fever

  • Interrupts your sleep

  • Affects sensitive areas like eyes, mouth, or genitals

If infection is suspected, look for redness, swelling, pain, warmth, pus, or a foul odor.

A Quick Review

Ringworm is a fungal infection with a characteristic red, circular rash. However, conditions like granuloma annulare, psoriasis, pityriasis rosea, and others may mimic its appearance. Because treatments vary depending on the condition, accurate diagnosis by a healthcare provider is essential before starting treatment.