Inverse psoriasis, sometimes called hidden psoriasis or intertriginous psoriasis, affects skin folds. These are areas of your body where skin rubs against skin.

Psoriasis is an autoimmune disease that affects your skin. Autoimmune diseases are conditions in which your immune system attacks your body. With psoriasis, your skin cells multiply too quickly.

The faster life cycle of skin cells causes various symptoms you’ll see on your skin. These include scaly, silvery lesions, red patches, and pus-filled sores.

Psoriasis tends to be pink or red on those with light skin tones, and the scale appears silvery white. On medium skin tones, it can appear salmon-colored with silvery-white scale. On dark skin tones, psoriasis could look violet or dark brown, sometimes with a grayscale.

Symptoms depend on the type of psoriasis you have. Inverse psoriasis is one of several types.

Inverse psoriasis, sometimes called hidden psoriasis or intertriginous psoriasis, affects skin folds. These are areas of your body where skin rubs against skin.

Inverse psoriasis can occur in any body area with creases, such as the neck, buttocks, under your arms, under your breasts, or in the groin or inner thigh area.

People with inverse psoriasis often have another form, such as plaque psoriasis, on other parts of their body. While raised lesions of dry, scaly skin – a key sign of plaque psoriasis – often cover large sections of your body, inverse psoriasis tends to appear in smaller patches.

Inverse psoriasis can appear in different locations. It may look different depending on a person’s skin tone.

Inverse psoriasis is known for its red, shiny, smooth rash. On dark skin tones, it may look dark purple, brown, or darker than the surrounding skin.

Unlike the scales, pustular spots, and crusting skin associated with other forms of psoriasis, the rash caused by inverse psoriasis is neither raised nor dry.

Inflamed patches of skin are sometimes moist to the touch. You may feel irritation, itching, or both in areas affected by inverse psoriasis.

You’re also at risk of developing a yeast infection in the skin folds due to the moist environment. The red lesions generally cover very large areas within your skin folds.

Inverse psoriasis is caused by an irregularity in your immune system, just like other autoimmune diseases. But moisture (in the form of sweating) and friction can trigger the symptoms of this type of psoriasis.

If you have psoriasis and are overweight or have obesity, you’re at a higher risk of developing inverse psoriasis. That’s because having a higher-than-moderate body weight produces excess skin and deeper skin folds.

Other causes or triggers can include taking certain medications, stopping or starting certain medications, infections, skin injuries, smoking, drinking alcohol, or friction within the deep skin folds.

There are several treatment methods for inverse psoriasis:

Topical treatment

Topical creams, types of medication that you rub into your skin, are typically first-line treatments for inverse psoriasis.

The treatment goal is to reduce inflammation and discomfort in these sensitive areas. Because skin folds are so sensitive, medications must be used carefully.

Steroid creams can reduce inflammation but can also cause the skin to become thinner and more sensitive. If you’re prescribed a topical treatment, your doctor will monitor your progress and adjust the dosage if there are signs of skin thinning.

Topical medications are typically used in the morning after you shower and before bedtime.

Alternatives to topical steroids are topical calcineurin inhibitors, tacrolimus, and pimecrolimus, which will stop the body’s immune system from producing substances that may cause skin disease.

Infected inverse psoriasis treatment

Inverse psoriasis is prone to yeast and fungal infections. This is because moist, inflamed skin provides an environment for bacteria or fungi to grow.

To counter this, doctors may also prescribe antibacterial or antifungal medications together with the typical psoriasis treatments.

Phototherapy

Phototherapy is a treatment option for people with moderate to severe inverse psoriasis. Phototherapy is the medical term for light therapy.

Ultraviolet light called UVB rays can slow the growth of skin cells in some people with psoriasis.

Treatment with phototherapy involves using a light box that produces artificial UVB rays for a specified time each session.

With phototherapy, your psoriasis might temporarily get worse before it gets better. Let your doctor know of any concerns about rashes during light therapy treatment.

Systemic drugs

If your inverse psoriasis is not getting better with topical medications and phototherapy, your doctor might prescribe systemic drugs. These are medications taken either by mouth or injection.

One type of systemic drug is a biologic, a medication that changes how your immune system works. Biologics use proteins to block your immune system’s response so that it will not attack your body as much.

If biologics are used as a treatment, your doctor will prescribe an injection or intravenous infusion of biologic drugs on a schedule. You might also continue with phototherapy or topical treatments at the same time.

Other systemic drugs that may be used are methotrexate or cyclosporine (Sandimmune), which moderate the immune system to decrease the action of certain skin cells.

The symptoms of inverse psoriasis can be uncomfortable. You can take certain steps to increase your comfort levels, physically and emotionally.

According to the International Federation of Psoriasis Associations, many people with psoriasis tend to wear loose clothing and avoid doing things that cause them to sweat. Both steps can help address symptoms.

Loose clothing, especially cotton or other natural fibers, allows your skin to breathe. Loose tops will not rub against your sore skin and can help prevent moisture from getting trapped in your skin folds.

You can also powder your affected areas with corn starch, baking soda, or zinc oxide to help absorb moisture. Consider trying out different styles of dress to determine what works best for you as you treat the condition.

Here are some answers to common questions about inverse psoriasis.

How do I know if I have inverse psoriasis?

Inverse psoriasis specifically affects the skin folds such as your armpits, under the breasts, or in the groin. Unlike regular psoriasis, the inflammation is moist and not dry.

How rare is inverse psoriasis?

The National Psoriasis Foundation reports that according to research, up to 30% of people with psoriasis also develop inverse psoriasis. But this prevalence rate varies widely according to different studies.

There isn’t a lot of data on the prevalence of inverse psoriasis among different groups. Generally, psoriasis occurs more often in people who are white. The data also indicates that only Asian people develop inverse psoriasis less frequently than other groups.

Is Vaseline good for inverse psoriasis?

Vaseline can be a good way to prevent flare-ups or reduce inflammation if you know you are going to engage in movement in the affected area. Vaseline can help protect the skin from friction that movement generates.

Inverse psoriasis causes inflammation in the skin folds. The causes or triggers can vary from friction in the area, having psoriasis elsewhere in the body, a higher-than-moderate weight (for example, overweight), and other lifestyle or health factors.

Inverse psoriasis causes a red, shiny, and smooth rash, which can look purplish or brown on dark skin.

Treatments can include topical and oral medications. Inverse psoriasis can become infected, so you may also need antibiotics or antifungal medications.

Living with psoriasis and inverse psoriasis can be physically uncomfortable and psychologically distressing. But there are ways you can help alleviate the symptoms.

Speak with your doctor to find out what treatment methods and supportive resources might work best for you.