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A widely-advertised facial moisturizer claims to be the best on the market 鈥� and sells for $225 per bottle. Should you buy it? Another brand offers a complete skin care regimen 鈥� but it comes in 10 different bottles of lotions and potions that all need to be applied daily. Is it worth your time?

Despite manufacturers' claims, many cosmetic products will remove more cash from your wallet than dirt and oils from your skin. You don't need an expensive or lengthy skin care routine 鈥� and the good news is, the most effective and reliable regimen is also quick and inexpensive.

Learn to spot an actinic keratosis before it becomes cancerous.

About 58 million people have at least one actinic keratosis (AK), a precancerous skin growth caused by too much sun exposure.

Yet most people don't see the potential danger in these lesions because they are small, with few if any annoying symptoms, and can go away almost as fast as they appear.

Lyme disease isn't the only cause for concern.

They may be as small as a poppy seed, but ticks are an increasingly large health risk for many Americans, especially in the warmer months.

Decades ago, it was thought that unless you lived in a Lyme disease hot spot, like Connecticut, that you didn't have to give too much thought to ticks and the illnesses they carry. However, that has not been the case for some time. In fact, tick-borne illnesses doubled in the United States between 2014 and 2016, according to the CDC.

On call

Q. Is there any difference between sunstroke and heatstroke and are there certain signs and symptoms I should look for?

A. These two terms refer to the same condition. Heatstroke (or sunstroke) happens when the body can no longer maintain a temperature of under 105掳 F when exposed to hot weather. People almost always have warning symptoms before heatstroke, yet sometimes they do not pay attention, or are not able to take action.

The first accurate medical discussion of psoriasis dates back to 1801, but the disease itself is much older. In fact, its very name is borrowed from an ancient Greek word meaning an itchy or scaly condition. About 7 million Americans are plagued by this itching and scaling, and many of them have serious complications involving other organs. Although psoriasis is classified as a dermatologic disease, it doesn't start in the skin, and its damage may be more than skin deep.

Beneath it all

At a basic level, psoriasis is a disorder of the immune system. White blood cells called T-helper lymphocytes become overactive, producing excess amounts of cytokines, such as tumor necrosis factor, interleukin-2, and interferon-gamma. In turn, these chemicals trigger inflammation in the skin and other organs. In the skin, the inflammation produces three characteristic findings: widened blood vessels, accumulation of white blood cells, and abnormally rapid multiplication of keratinocytes, the main cells in the outer layer of the skin. In healthy skin, keratinocytes take about a month to divide, mature, migrate to the skin surface, and slough off to make way for younger cells. But in psoriasis, the entire process is speeded up to as little as three to five days. The result is thickened, red skin that sheds silvery scales of keratinocytes that have matured before their time (see Figure 1).

Q.聽I'm 63, and I've begun to notice a decline in the quality of my fingernails. They have numerous up-and-down ridges, and at the tips, they're always splitting. I've heard you can tell a lot about a person's health from the condition of her nails. What does my split nails say about mine?

A.聽Some changes in nails can be a sign of an underlying health problem, but the lengthwise nail ridging you describe is usually not one. It's simply a common sign of normal aging. The growth of fingernails and toenails slows as we get older, and their appearance may change. Some nails become yellowed or dull and brittle, and some or all may develop tiny longitudinal ridges. Fingernails tend to become thinner and more fragile, while toenails usually become thicker and harder.

Research we're watching

If your hair has been thinning, an infusion of your body's own plasma may help grow it back, according to the American Academy of Dermatology.

A number of recent studies show that platelet-rich plasma (PRP) therapy is successfully regrowing lost hair. This includes a 2018 study in the International Journal of Women's Dermatology that found the technique was beneficial in treating androgenetic alopecia, a type of genetically and hormonally driven hair loss that affects as many as 35% of women by age 60.

There are lots of dubious claims and mysterious ingredients, but yes, by trapping water, moisturizing can help with dry skin.

Dry skin by itself isn't a medical worry, although serious cases can result in cracks and fissures that invite infection and inflammation. The real issue is discomfort 鈥� dry skin can be sore, tender to the touch, and often itchy (although not all itchy skin is dry). There's also the red, rough, scaly appearance lamented in many advertisements for moisturizers.

This is one problem that hasn't suffered from lack of attention: there are dozens of creams and lotions for dry skin. They are sold as moisturizers, which is more of a marketing term than a medical or scientific one. Indeed, routine skin care is a realm where there's little science to be found. Well-controlled studies of ingredients are few and far between. Companies keep information about ingredients proprietary and are careful to limit claims for what the products do to stay within FDA rules.