- With Mayo Clinic dermatologist
Lawrence E. Gibson, M.D.
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Lawrence E. Gibson, M.D.
Lawrence E. Gibson, M.D.
Dr. Lawrence Gibson likens bad health information on the Internet to food poisoning.
Consumers, he said, need to be aware, and will find reliable information at MayoClinic.com.
Dr. Gibson, a Covington, Ky., native, has been with Mayo since 1986 and is board certified in dermatology, dermatopathology and immunodermatology. He is a professor of dermatology at Mayo Medical School and a consultant in the Department of Dermatology.
Dr. Gibson has been director of the Dermatopathology Laboratory since 1998 and chair of the Laboratory Division in the Department of Dermatology since 2000. He is especially interested in inflammatory disorders of the skin and lymphoma affecting the skin.
"Electronic information is becoming a staple in the diet of a health conscious society," he said. "It's important to avoid misinformation and provide a credible source for health information. Using this analogy, it's critical to avoid 'indigestion' or worse yet, 'food poisoning' by the ingestion of tainted information."
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Question
Does sunscreen expire?
I have an old bottle of sunscreen from last year. Is it still good? Or should I throw it out?
Answer
from Lawrence E. Gibson, M.D.
Sunscreens are designed to remain stable and at original strength for up to three years. This means that you can use leftover sunscreen from one summer to the next.
Some sunscreens include an expiration date — the date at which time the sunscreen is no longer effective. Discard sunscreen that is past the expiration date or is more than 3 years old.
Keep in mind, however, that if you use sunscreen frequently and liberally, a bottle of sunscreen shouldn't last you that long. A liberal application is 1 ounce (30 milliliters) — the amount in a shot glass — to cover all exposed parts of the body. If you have a 4-ounce (118-milliliter) bottle, you'll use about one-fourth of it for one application. Be sure to rub the sunscreen in well.
To maximize protection, use a broad-spectrum sunscreen with a sun protection factor (SPF) of at least 15. Apply liberally 30 minutes before going outdoors and reapply every two hours, or after swimming or sweating.
Next questionSleep guidelines: How many hours of sleep are enough?
- Sunscreen drug products for over-the-counter human use: Final monograph. Food and Drug Administration. http://www.fda.gov/cder/fdama/fedreg/sunscreen.pdf. Accessed Jan. 29, 2009.
- U.S. Code of Federal Regulations: 211.134 Drug product inspection. Food and Drug Administration. http://edocket.access.gpo.gov/cfr_2008/aprqtr/pdf/21cfr211.134.pdf. Accessed Jan. 29, 2009.
- Choose your cover: Questions and answers. Centers for Disease Control and Prevention. http://www.cdc.gov/cancer/skin/chooseyourcover/qanda.htm. Accessed Jan. 29, 2009.
- The burning facts. Environmental Protection Agency. http://www.epa.gov/sunwise/doc/sunscreen.pdf. Accessed Jan. 29, 2009.
- Facts about sunscreen. American Academy of Dermatology. http://www.aad.org/media/background/factsheets/fact_sunscreen.htm. Accessed Jan. 29, 2009.
