If you develop raised red patches with a silvery-white coating over your knees, elbows, lower back, or scalp, you probably have plaque psoriasis. It’s the most common form of psoriasis, a chronic disease that seriously speeds the process by which skin cells mature and reach the skin’s surface. Because the rate at which old cells are shed remains unchanged, the new cells stack up and become thickened patches covered by the dead, flaking skin.
The precise cause of psoriasis isn’t known. “Something is happening at the level of the T-cell, one of the immune cells in our body, that signals the skin to overproduce,” explains Mona Gohara, MD, associate clinical professor of dermatology at Yale School of Medicine. Heredity is definitely a factor—about one-third of sufferers have a close family member who’s also affected, according to the National Psoriasis Foundation. Psoriasis can begin at any age—“You can come out of the womb with it or develop it late in life,” says Dr. Gohara—but most people get it between ages 15 and 30. Three-quarters of people who are going to develop psoriasis have it by age 40.
Psoriasis can come and go with varying degrees of severity, and attacks may be triggered by emotional stress, skin injury, and physical illness. There’s no cure for the condition, but many treatments are available, and your dermatologist will chose the right one based on the degree of your psoriasis and where on the body it occurs.
Eczema can be exacerbated by a variety of things, including hot baths and heavy use of soaps; tight, scratchy clothing; anything that makes your skin hot and bothered, such as sunbathing or excessive sweat-inducing exercise; scratching, which only inflames the already irritated skin even more; and stress, which can precipitate or aggravate an outbreak. Everybody’s eczema triggers are different, though, so it’s important to identify yours. There’s no cure for eczema, but there are many treatments, including over-the- counter remedies, prescription meds, light therapy, immunosuppressants, and biologic drugs. But self-care, including regular use of a moisturizer with a high oil content to keep the skin hydrated and less reactive, is key to managing flares.
Yeast on the skin can also cause tinea versicolor, a condition that triggers dry, scaly, discolored patches on areas of high sweat—usually the neck, chest, back, and groin. “Yeast loves moist environments, so when some people sweat, it overgrows,” explains Dr. Gohara. The spots can be lighter or darker than your skin and may itch. The spots may become more noticeable after spending time in the sun.
Tinea versicolor is very common in tropical or subtropical areas of the world; some people who live in these environments have it year-round. The solution is the same as for seborrheic dermatitis: “Reel the yeast in with an antifungal shampoo,” says Dr. Gohara, who recommends using it head to toe every day for a month and then once or twice a week for the following month to maintain the results. Tinea versicolor often returns, especially if you live in a warm, humid environment, so using an antifungal cleanser once or twice a month can help prevent the yeast from overgrowing again.
These crusty, scaly, precancerous growths form on skin that soaks up a lot of sun over the years. The most common spots for actinic keratosis are the face, ears, bald scalp, shoulders, neck, forearms, and the backs of the hands. Actinic keratoses develop slowly and initially are felt rather than seen: “It’s like you’re running your finger over sandpaper,” says Dr. Gohara. Most actinic keratoses become red, but some are light or dark tan, white, pink, and/or flesh- toned, or even a combination of these colors. Often several actinic keratoses show up at the same time, and they may disappear only to reappear later. The growths are considered precancerous because if left alone, they could turn into a type of skin cancer called squamous cell carcinoma. “Only one in 1,000 develops into cancer, but since the potential is there, actinic keratoses should be treated,” says Dr. Gohara. Treatment typically includes one of a number of different surgical procedures to remove the growth or the use of a prescription medication.
From fragrance to hair dye, there are many things you might put on your skin that you could be allergic to—and those irritants can cause inflammation that leads to itching, redness, and rough, scaly skin, technically called allergic contact dermatitis. Nickel is a common culprit: Between 10% and 20% of people are sensitive to this metal, according to the CDC, and nickel allergies affect more women than men.
Especially at an early stage, squamous cell carcinoma (SCC), the second most common form of skin cancer, typically appears as scaly patches on areas of the body that receive a lot of sun exposure. (The name makes sense, since “squama” is Latin for scale.) These spots can also look like warts and sometimes appear as open sores with a raised border and a crusted surface. Unlike dry skin, these lesions, which range from pea-size to chestnut-size, can bleed if bumped, scratched, or scraped. They may persist, but they can also heal and then return. Anyone can develop SCC, but people with fair skin, light hair, and light eyes are at highest risk. SCC can become disfiguring and sometimes deadly if allowed to grow, so be sure to see your doctor if you notice any change in a preexisting skin growth or the development of a new one.
An underactive thyroid, also called hypothyroidism, can affect many parts of the body, and the skin is no exception. A small gland that sits at the base of your neck, the thyroid produces hormones that control your metabolism. Along with feeling colder and sluggish and becoming forgetful and depressed, having a thyroid that produces too little thyroid hormone leaves many people with dry, rough, and scaly skin.
If you think you might have an underactive thyroid, your doctor can confirm it with a series of blood tests. The most common reason your thyroid gland can’t make enough thyroid hormone is due to an autoimmune disease like Hashimoto’s disease, in which your immune system mistakenly attacks your thyroid gland.
This disease gets its name from the Greek word for fish, and that’s no accident: When someone has ichthyosis, the skin often looks like it’s covered in fish scales. Ichthyosis results from the same gene mutation that may cause eczema that results in having too little filaggrin in your skin. Without enough of this protein, skin cells aren’t shed as they should be and tend to pile up on the surface, causing thickened, scaly skin, explains Dr. Gohara.
Scaly skin due to a peeling sunburn might not seem like a good thing at the time, but it’s actually how the body gets rid of the UV-damaged cells, explains Steven Wang, MD, director of dermatologic surgery and dermatology at Memorial Sloan-Kettering Cancer Center at Basking Ridge, New Jersey, and chair of the Skin Cancer Foundation’s Photobiology Committee. “As a reaction to the massive UV assault, the cells commit suicide as a way to prevent those with an excessive amount of DNA mutation from propagating.” Unfortunately, this process isn’t perfect, and some of the surviving cells stick around and cause further mutations that could eventually become cancerous. Scary stat: A single blistering sunburn in childhood or adolescence more than doubles your risk of developing potentially deadly melanoma later in life.
If you get burned, take quick action to prevent peeling: Cool your skin with cold compresses or take a cool shower or bath, then moisturize skin while it’s still damp (steer clear of petroleum or oil-based ointments that can trap heat and make the burn worse, advises the Skin Cancer Foundation). To avoid getting burned in the first place, apply a broad-spectrum sunscreen with an SPF of 30 or higher on all exposed skin; seek shade whenever possible; and cover up with hats, sunglasses, and UV-protective clothing.
You don’t have to be an athlete to get this fungal infection, but the warm, dark, moist environment inside a sporty sneaker is the perfect place for fungus to grow, says Brian Adams, MD, a dermatologist in Cincinnati and chair of the American Academy of Dermatology Sports Committee. The condition is particularly common between the toes, though it often spreads to the soles, the heels, and the edges of the feet. The fungus can cause skin to redden and crack, and the affected scaly areas flake and may become itchy.
Unlike most other causes of scaly skin, athlete’s foot is highly contagious. It’s also difficult to get rid of, so prevention is key. Athletes should opt for synthetic, moisture-wicking socks, which keep feet cool and dry, and wear flip-flops in community locker rooms and showers—contracting athlete’s foot is as easy as stepping on a tiny flake of skin from someone with the infection. Topical antifungal creams, gel, or sprays usually clear the infection quickly, but to be sure the skin is completely free of the fungus, you may need to treat it for a week or two after the rash has gone (follow the instructions on the label). Many other problems of the feet—including contact dermatitis, psoriasis, and dryness—may mimic athlete’s foot, so if the problem persists, see a dermatologist.
This rash follows a very distinctive pattern, appearing first on the body as a single, oval, scaly patch. Known as the “herald” or “mother” patch, this isolated spot usually develops on the trunk, upper arms, neck, or thighs, and rarely, on the face, scalp, palms, and soles. “Then, a couple of weeks later, you erupt in smaller patches from your neck to your thighs,” says Dr. Gohara. One telltale sign of pityriasis rosea: The patches often form a pattern that resembles a Christmas tree.
The cause of pityriasis rosea isn’t known, but it’s thought to be triggered by a viral infection. What is known is that the condition is harmless, neither contagious nor sexually transmitted, and usually clears up on its own after a month or two without treatment—though doctors may prescribe topical steroids if the skin itches, as it does about half the time. (Tip: Getting overheated can worsen the rash, so take lukewarm showers and baths.) “Pityriasis rosea can really freak people out because it’s this weird thing that pops up, and then it just sort of goes away leaving no trace,” says Dr. Gohara. See a doctor if you think you have this distinctive rash.