Q. If I had the time, I'd research everything about sun protection. But why should I? That's your job. What must I absolutely know about sunscreen?
1. Wear it. All over. Recently, on a Florida beach, I realized I hadn't applied sunscreen on my toes, which had been peeking innocently out of the umbrella shade. Zorched. Remember to use an SPF of at least 15 on your lips, too, because they're often exposed, says Debra Jaliman, MD, assistant clinical professor of dermatology at Mount Sinai School of Medicine. Also on your ears, your Achilles tendon and anything else that happens to stick out. A shot glass full should be enough to cover you.
2. Use a broad-spectrum product—one that blocks UVA (more deeply penetrating) and UVB (burning) rays. Look for one containing either zinc oxide or titanium dioxide (physical sunblocks) and/or Parsol 1789 (a chemical ingredient also called avobenzone), or Mexoryl, all of which provide considerable UVA protection.
3. Reapply. Even if the residue from the creamy base of the product remains on your skin, the block or screen may not. Coat yourself every two hours, says David H. Herschthal, MD, professor of dermatology at the University of Miami School of Medicine. At the beach or pool, a water-resistant product may not wash off but may rub off after you towel yourself dry, so you'll still need to reapply.
4. Choose a sunscreen suitable for your skin type. If you have dry skin, look for an emollient cream and avoid products with an alcohol base. Liquids and gels are better suited to oilier skin.
Keep reading: Readers share their sunscreen stories
Q. I'm suspicious of marketers. Do people like me with very dark skin really need sunscreen?
A: You may not get sunburned, and the melanin in your skin will protect you longer, says Herschthal, but the radiation from UVA rays can still cause wrinkles and even skin cancer.
Keep reading: Tips for different skin types
Q: How do firming body lotions work?
A: A colleague here in the office claims that she gets a tighter bottom when she applies firming body lotion. One of the reasons I'm fond of her is that, among her many other lovely qualities, she is a terrific optimist. I say, if you think your bottom looks better and that makes you happy (and why wouldn't it?), more power to you. Keep using the stuff. But in the sometimes dark and often skeptical world of Ask Val, firming lotions are good for one thing only: moisturizing. That will improve the appearance of the skin temporarily, says Arielle N.B. Kauvar, MD, clinical associate professor of dermatology at New York University Medical Center. The antioxidants added to some formulas may help reduce collagen breakdown but will not stimulate new collagen and skin thickening, Kauvar says.
Bottom line: Though firming lotions can plump up your skin with moisture, there's no evidence that the ingredients produce long-term effects.
Q: Do creams and lotions containing collagen deliver it into the skin?
A: "There has been no scientific evidence to suggest that there is enough penetration of collagen transepidermally to be deposited in the dermis," says Neil Sadick, MD, clinical associate professor of dermatology at New York Presbyterian Hospital–Weill Cornell Medical Center in New York City.
Bottom line: The doctor said no.
Keep reading: What women doctors know about skincare (that you should too)