Just noticed an itchy, red area on your arm or leg? Among the many skin conditions that could be to blame, psoriasis and ringworm are two that can easily make the list of suspects to the untrained eye. Here’s what to know to help tell them apart.
How to Tell Ringworm From Psoriasis
Ringworm is the common name for an infection, called tinea. The name comes from the shape of the rash, a thin red circle with a clear middle. But it has nothing to do with a worm and everything to do with a fungus. Skin can get scaly too as ringworm progresses.
Psoriasis is an autoimmune disease that leaves a stamp on your skin. It starts as rough, scaly red patches that can become covered by thick, silver-colored scales. The patches aren’t just itchy, they can also be painful.
Both conditions cause redness, so it can be hard to tell them apart at first. But as they progress, it’s often possible to see the differences.
How the Conditions Are Similar and Different
The similarities. Psoriasis and ringworm can show up almost anywhere on your body. Psoriasis most often develops on the lower back, legs, elbows and knees, palms and soles, and the face and scalp. But you may also have patches on your eyelids, ears, lips, skinfolds, the tops of hands and feet, and even your nails.
You can get ringworm almost anywhere, too. It’s often on the torso, buttocks, arms, and legs. It all depends on which part of your body came into contact with the fungus. Location also determines what the infection is called. For instance, there’s athlete’s foot or tinea pedis, jock itch or tinea cruris, and scalp ringworm or tinea capitis.
The differences. Psoriasis is an autoimmune disease, so it’s a systemic, or bodywide, condition. Your immune system is sending out the wrong signals, creating inflammation and causing skin cells to multiply too fast. You can treat psoriasis, but it’s never really cured. All it takes is a trigger to cause a new flare. On the other hand, because ringworm comes from an outside source (the fungus), once treated it’s usually gone, even if treatment takes weeks or months.
Psoriasis is not contagious. You can’t pass it to someone or get it from someone. The opposite is true for ringworm. It’s very contagious. In fact, the most likely way to get it is from skin-to-skin contact with someone who has it.
What Causes the Conditions?
The ringworm infection comes from a fungus that takes up residence on your skin’s outer layer. Besides person-to-person contact, you can get it from your pet or another animal or from an object that someone with ringworm has used, like a towel or a hairbrush. It’s rare but possible to pick up the fungus from soil if you were exposed to it for a long time.
We still don’t exactly understand why someone might develop psoriasis. Like other autoimmune diseases, it’s probably a combination of the genes you’re born with and things in the world around you that act as triggers. Those can include infections, an injury to the skin, smoking, drinking, and even stress.
What Are the Symptoms of Ringworm and Psoriasis?
Ringworm symptoms include:
- A ring-shaped rash with clear skin inside. Sometimes, that skin is scaly or bumpy.
- The entire area may be itchy but usually isn’t inflamed.
- You may have multiple rings, and they may expand, overlap, and be raised and scaly.
More specific symptoms depend on where and how severe the infection is. For example, you may get a red, swollen, and even oozing patch of skin with scalp ringworm or fluid-filled spots when it’s on your foot.
Psoriasis symptoms include:
- Skin plaques made up of red patches, often covered by thick, silver-colored scales
- Cracks in the skin that may bleed
Psoriasis symptoms vary from person to person and even from flare to flare because everyone’s disease is different. Psoriasis can affect your nails. They may get thicker and develop pits or ridges. And it can affect your joints (psoriatic arthritis). They may feel stiff and look swollen.
How the Conditions Are Diagnosed
Some of the steps your doctor or dermatologist will take are very similar, like asking questions about your health and looking at the affected areas. Doctors can often identify ringworm and psoriasis from the way they look. But to learn more, your doctor may send a small skin sample to a lab for a detailed look. With psoriasis, this helps determine which of the many types you might have. With ringworm, it helps pinpoint the exact fungus that’s to blame. Either way, this information will help you get the right treatment.
If You Think You Might Have Ringworm or Psoriasis
Talk to your doctor if you have a rash that doesn't get better or worsens, no matter what it looks like, because both conditions need specific treatment.
For mild ringworm, you’ll probably apply an antifungal medication to your skin. For more severe infections, you may need pills.
There isn’t a cure for psoriasis, but medications can ease mild symptoms. Stronger drugs like biologics, which target specific parts of your immune system, can clear plaques completely for many people.