Causes of a red circle on the skin other than ringworm

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Pityriasis rosea is a common, mild skin rash that may last for 6–8 weeks and often clears up on its own.

The initial signs of infection include headache, fever, and cold-like symptoms. Soon after, a single scaly patch, about 2–10 centimeters (cm) in size, forms on the torso or neck.

When the first patch appears, it can be mistaken for ringworm. As the condition runs its course, the rash spreads out into larger blotches.

The rash is not painful but may be itchy. In those with darker skin tones, it may appear gray, dark brown, or black and can cause flat dark spots lasting several months. In those with lighter skin tones, it may appear pink or red but rarely forms scars.

The cause of pityriasis rosea is most likely the cold sore virus. But rosea sores are not contagious and cannot spread to others through physical contact. Also, pityriasis rosea can occur a couple of weeks after a COVID-19 infection.

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Contact dermatitis is a form of eczema that results from something coming into contact with the skin.

As contact dermatitis can cause patches of thickened, scaly skin, it can be confused with ringworm. The patches may appear dark brown, purple, or gray on darker skin tones, while they usually appear bright red on lighter skin tones.

A person with contact dermatitis may be allergic to certain metals, such as nickel or cobalt, ingredients in cosmetics or soaps, or materials such as latex.

“Contact dermatitis” can also describe skin irritations such as diaper rash or cracked skin after too much handwashing or dishwashing. In severe cases, the area may bleed or ooze.

Nummular eczema, also known as discoid eczema, is a disorder that causes coin-shaped patches of itchy, swollen skin to appear. This type of eczema occurs mainly on hands, arms, or legs and sometimes on the trunk.

Ringworm and nummular eczema both look similar because of a circular rash pattern. However, nummular eczema starts as tiny spots that turn into a rash. In contrast, ringworm spreads out with a clear center encircled by a discolored ring.

These spots measure 2–10 cm across, although they may be smaller. On lighter skin tones, they appear scaly and pink or red. The areas will look much darker or lighter on darker skin tones. Itching or burning sensations in these areas worsen at night and can be severe. Often, patches will flare up in the same spots on the body, and in serious cases, patches can leak fluid or crust over.

It is not clear what causes nummular eczema. Dry skin, extreme stress, sensitivity to a particular metal, and medication may all be triggers. Also, the symptoms worsen in cold, dry climates and in people with poor blood circulation.

Granuloma annulare is a rare, chronic skin disorder that is not contagious or cancerous. Although the affected skin looks like ringworm, the center of the rash remains a solid color.

In this condition, a raised round rash forms with a distinctive border of small, firm bumps. These bumps grow into a ring and mainly develop on the feet, legs, hands, or arms. The rash can appear deeper in color on darker skin, with a purplish-red edge around the outside. On lighter skin tones, the site may be yellow, red, or flesh-colored.

The rash is not usually painful or itchy and will often fade without treatment. There are many types of granuloma annulare, but the most common type is localized, primarily affecting children.

Experts are not sure exactly what causes granuloma annulare, but it may involve:

• injury to the skin with a bug bite, tattoo, or stitches
• taking certain medications, such as calcium channel blockers or ACE inhibitors
• viral infections, including shingles or HIV
• specific health issues, such as diabetes or thyroid disorders

Psoriasis is a common long-term skin condition that develops when the body produces skin cells too quickly. As a result, the cells pile up, forming visible patches on the skin’s surface.

In the beginning, psoriasis and ringworm look similar in color and shape. Yet, psoriasis does not go away with antifungal cream and worsens over time.

Psoriasis can form anywhere on the body, but it typically appears on the elbows, knees, scalp, and lower back. Patches will appear rose-colored on darker skin and dark red or purple on lighter skin.

In addition, a crusty white, yellow, or silvery layer of skin can form over the patches, regardless of the skin tint. For some people, the spots can grow into the joints and nails. In severe cases, people may have difficulty walking or using their hands or arms.

Symptoms include itching, soreness, or a burning sensation at the site. Skin cracks and bleeding can occur in repeated flares, putting the area at risk for infection.

Experts believe psoriasis comes from issues with the immune system causing the body to attack healthy skin cells. It is not contagious, but it can run in families — though it is not always hereditary. The following factors can trigger psoriasis:

• hormonal changes
• excessive alcohol intake
• stress or anxiety
• injuries to the skin, including insect bites and sunburn
• infections such as strep throat
• certain medications, such as anti-inflammatory drugs or high blood pressure medications

Depending on the type of psoriasis, the patches may heal and not return for months. However, most cases will require medication for long-term management.

Lyme disease is a bacterial infection caused by the bite of a black-legged deer tick.

People with Lyme disease develop a circular bull’s-eye rash around the bite mark. This “target” rash can sometimes be confused with ringworm.

Up to 70% of people in the initial stage of Lyme disease will have a rash appear within 5–7 days after the bite. The area may burn, itch, or feel hot to the touch.

The center of the rash may contain a bite mark and look like a bruise. On lighter skin tones, the spot will be bright red. However, on darker skin tones, a pinkish-brown ring may appear around a maroon-red area. Also, the bull’s-eye rash may be harder to see on those with darker skin.

With or without rash, Lyme disease can cause flu-like symptoms, such as a fever, muscle aches, and fatigue. If left untreated, the symptoms can progress into pain and swelling in the joints, numbness in the hands or feet, and heart or brain damage.

Not all tick bites progress to Lyme disease, but a person should consult their healthcare professional if bitten.

Lupus is a chronic inflammatory disease that can cause a scaly rash to form on the upper body and face. During a first-time flare, this rash can resemble ringworm.

Since skin symptoms of lupus form on skin exposed to sunlight, a person with lighter skin may develop a pink spot with a dark-brown border on their face, neck, arms, or hands. On a person with darker skin, it may be dark black or light pink with a maroon edge. Lupus flares may form scars as they heal.

A person with lupus may also experience:

• fatigue
• joint weakness
• flu-like symptoms

The following factors may trigger flare-ups:

• exposure to sunlight
• stress, excess work, or lack of sleep
• infection
• injury

The symptoms may flare up for a few weeks or longer before improving. Since lupus is a chronic condition, flares can happen again in the same spots or in new areas.

The proper treatment approach for a red, circular rash depends on the cause, and an accurate diagnosis is key.

Depending on the severity of the rash and any other symptoms, a person may benefit from a combination of the following treatments and home care strategies:

Avoiding triggers

Conditions such as contact dermatitis, nummular eczema, psoriasis, and lupus can occur or flare up in response to triggers. Identifying and avoiding specific triggers can help keep the symptoms at bay.

Emollients

Emollients are moisturizing treatments that help soothe and hydrate the skin, reduce itchiness, and prevent inflammation. People with contact dermatitis, nummular eczema, and psoriasis benefit most from these products.

They come as lotions, creams, ointments, or soap substitutes. In most cases, a person can purchase emollients from a pharmacy without a prescription.

However, it is essential to know that emollients containing tree nuts may worsen certain skin conditions. A doctor or pharmacist can help choose a safe product.

Topical treatments and drugs

Professional treatment for these conditions often starts with an ointment or cream, which may contain steroids or antibiotics. A healthcare professional may also recommend steroid injections or tablets, oral antibiotics, or anti-allergy medications.

However, for Lyme disease, antibiotic tablets or injections are the first-line treatment.

For psoriasis, a wide range of medicated creams include:

• coal tar, a thick oil, to reduce itchiness and swelling
• synthetic vitamin A or D creams to slow skin cell production
• calcineurin inhibitor creams, such as pimecrolimus or tacrolimus, for off-label use to suppress the immune system

Even after a person uses topical treatment and steroids, severe cases of psoriasis may require an oral or injectable biologic drug.

For lupus, doctors may prescribe calcineurin inhibitor creams, chemotherapy, or malaria treatment.

Other therapies

Some forms of light therapy, such as ultraviolet light therapy, may help with pityriasis rosea, granuloma annulare, nummular eczema, and psoriasis.

Cryotherapy, which involves freezing areas of skin with liquid nitrogen, can help control granuloma annulare.

If an unexplained rash lasts longer than a few weeks, reach out to a doctor, such as a dermatologist.

It is essential to receive professional care if the rash:

• appears over the whole body
• is painful
• seems infected
• produces blisters, especially near the eyes, inside the mouth, or near the genitals
• occurs with any fatigue or joint pain

The American Academy of Dermatology recommends seeking emergency care if a rash:

• accompanies a fever
• accompanies difficulty breathing
• appears suddenly and spreads quickly

Rashes that are circular and scaly do not always indicate ringworm. Instead, they can result from several common health issues, some more serious than others.

Different treatments are available, and the best approach depends on the rash’s cause and severity.

Anyone with an unexplained rash should receive a professional diagnosis. If a rash appears and spreads quickly, or if it occurs with a fever or difficulty breathing, contact emergency services.