Dear Doctors: I recently developed very bad psoriasis, but only on my scalp. The itch is awful. I'm not interested in the medications advertised on TV because of the side effects. Can you recommend anything?

Dear Reader: Psoriasis is a chronic inflammatory condition in which a glitch in the immune system causes skin cells to multiply at an abnormally fast pace. This results in raised patches of scaly, reddened skin. Known as plaques, they are often itchy and can be painful.

On light-skinned people, a buildup of dead skin cells makes them appear silvery. In darker skin, plaques have a brown, gray or purplish hue. Although psoriasis can develop anywhere on the body, it occurs most often on the skin of the elbows, torso, knees and scalp. In some people, as in your case, symptoms are confined to the scalp. This results in powdery, scaling skin that often looks like dandruff.

When you say you're not interested in the newer psoriasis treatments, we suspect you're referring to a class of medications known as biologics. They work by calming the part of the immune system involved in the overgrowth of skin cells. Biologics are effective, and because they are targeted, there is a reduced risk of their causing problems to your kidneys, liver or other organs. However, as with any medication, they can cause side effects. These include headache, injection site reactions, upper respiratory infection and urinary tract infection. If you change your mind, your doctor can help you explore this option.

There is a range of other treatments for scalp psoriasis. Topical corticosteroids, such as clobetasol propionate, are effective at managing symptoms, including itching. For scalp psoriasis, they are available in medicated shampoos. These can be safely used regularly for several weeks to ease symptoms. After that, weekly or semi-weekly use is usually adequate for maintenance.

As with all corticosteroids, side effects are possible. These include redness and burning, thinning of the skin, skin dryness and acne. Corticosteroids can interact with certain medications, including aspirin. They should not be used when other medical conditions are present, including diabetes. Anyone using corticosteroids should follow directions carefully.

Additional treatments include salicylic acid, which can soften plaques. Retinoids, used to treat acne, can slow overgrowth and ease inflammation. A topical retinoid cream known as tazarotene is sometimes prescribed for psoriasis. Coal tar, a type of creosote, may also reduce inflammation and slow cell growth. It is available over the counter in many forms, including shampoo. Some people find relief with specialized laser and other light treatments. A dermatologist can explain the available options.

Lifestyle changes are also important. Psoriasis flares and ebbs, and you may find a connection to certain foods, climate or behavior. Don't try to manually reduce plaques or remove psoriasis “dandruff,” as this may increase inflammation. Because scalp psoriasis can occur in tandem with psoriatic arthritis, it would be wise to see a dermatologist for a definitive diagnosis. Depending on your symptoms and medical history, they may refer you to a rheumatologist.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o UCLA Health Sciences Media Relations, 10960 Wilshire Blvd., Suite 1955, Los Angeles, CA, 90024. Owing to the volume of mail, personal replies cannot be provided.)

Dear Doctors: I love decaffeinated black tea and drink a lot of it. Since I don't add sugar or milk, I have always felt it was healthy. Now I'm questioning that assumption because I've heard that the decaffeination process can make the tea unhealthy. Should I be cutting back?

Dear Reader: Caffeine is an organic compound that occurs naturally in more than 60 plants. It is highly soluble in warm water, which makes it easy to extract for use in beverages.

Here in the United States, the most common natural sources of caffeine are coffee beans, tea leaves, kola nuts and cacao pods. The first two are self-explanatory. Kola nuts are used to flavor soft drinks, and cacao pods are the basis for chocolate products. Growing in popularity are yerba mate and guarana, plants that hail from South America. Caffeine also exists in synthetic form. It is widely used in energy drinks and is added to some foods and over-the-counter medications.

Because caffeine acts as a stimulant on the central nervous system, it meets the criteria of being considered a drug. It gives a boost to energy and mood and helps with wakefulness. However, the physical effects of caffeine don't end there. It can also increase stomach acid, affect how the body uses glucose, raise blood pressure, stimulate the bowels, act as a diuretic, adversely affect heart rhythms and interfere with sleep.

The way the body processes caffeine changes as we age. Older adults metabolize it more slowly, and some find that even small amounts can cause disturbed sleep.

Whether due to health issues or as a personal choice, some people steer clear of caffeine. But thanks to the process of decaffeination, they can continue to enjoy beverages that would otherwise be off-limits. The most common method uses chemical solvents -- typically ethyl acetate or methylene chloride -- to remove caffeine. The process includes a step in which the solvents are rinsed, evaporated or vaporized away. However, the final product does contain trace amounts of the solvent that was used. A small amount of caffeine remains as well.

Both tea and coffee can also be decaffeinated via a process that uses carbon dioxide and activated carbon filters. It's a bit more costly to produce decaf teas and coffee this way, and they may not be as widely available.

When it comes to choosing decaffeinated products, beverage drinkers need to consider both the presence of residual solvents, as well as the small amount of caffeine that remains in the product. The solvents are highly volatile chemicals that vaporize at under 125 degrees. Coffee roasts at 400 degrees, and black tea is fermented at about 160 degrees, each well above the temperature at which the solvents are destroyed. The amount of caffeine that remains varies depending on the product. Tests show it ranges from about 2% to about 10%.

Since your concern about decaf tea arises from the potential presence of solvents, consider seeking out products that use the carbon dioxide method. You might also give the fascinating, flavorful and naturally caffeine-free world of herbal teas a try.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o UCLA Health Sciences Media Relations, 10960 Wilshire Blvd., Suite 1955, Los Angeles, CA, 90024. Owing to the volume of mail, personal replies cannot be provided.)

Dear Doctors: I've noticed that as I get older, jet lag hits me harder. I recently read that timing your meals on the day you fly can make a difference. Do you know if that's true? I'm also curious about apps like Timeshifter, which my son swears by. Can they help?

Dear Reader: Jet lag is the collection of unpleasant symptoms that occur when a flight takes you across multiple time zones. When you arrive, your body's inner clock is out of sync with your destination, and that exacts a physical toll.

Symptoms of jet lag include daytime fatigue, low mood, disordered sleep, brain fog and a general feeling of malaise. Some people experience gastric problems, including diarrhea or constipation. Traveling west is easier on the body clock than traveling east, because it prolongs the normal day-night cycle, but the more time zones that are involved, the greater the net effects of jet lag. And as you have discovered, the effects of jet lag can become more pronounced and harder to shake off as we age.

The challenge of jet lag lies in the complexity of our bodies' circadian rhythms. Also referred to as the body clock, they are synced to our planet's 24-hour cycle of daylight and darkness. Circadian rhythms trigger the hormonal, neural and other changes in the brain that oversee sleep and wake patterns. They also affect mood and cognition, are influenced by physical activity and control how our bodies process nutrients.

Making things even trickier is newer research that suggests each cell has its own internal clock. Emerging evidence also shows that exposure to as little as five minutes of bright light can cause the circadian system to reset and recalibrate. With so many intricate and interlocking biological systems involved, it's easy to see how the problem of jet lag remains unsolved.

Resetting the body clock during travel typically takes about one day per time zone crossed. Popular strategies to speed recovery include scheduling exposure to light or dark, taking melatonin to signal sleep and using sleep medications.

In a study published last fall, researchers from Northwestern University explored a possible role for food in managing jet lag. They found that scheduling meals to match the new zone helped to reset the body clock. Someone traveling to Europe from New York on an evening flight, for example, would have a light dinner and avoid eating on the flight. Upon arrival in the morning, they would have a hearty breakfast. That, along with deliberate exposure to bright daylight, was found to cut the typical six-day recovery time by as much as one-third.

Apps like the one your son recommends use each person's travel information to craft a detailed jet lag recovery schedule. This includes exposure to light and darkness and optimal sleep and wake times, both before the trip and after arrival at the destination. Some include an alarm function synced to gradually awaken the individual during a cycle of light sleep, which can help to minimize grogginess. Although scientific proof of their efficacy is lacking, anecdotal evidence suggests these apps can be helpful.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o UCLA Health Sciences Media Relations, 10960 Wilshire Blvd., Suite 1955, Los Angeles, CA, 90024. Owing to the volume of mail, personal replies cannot be provided.)