Jump to content

  • Set Your Location
  • Sign in or Enroll
Set Your LocationSet Your Location
  • Sign in or Enroll
    • Open I want to choose my medical group or hospital
    • Clear my location
Change Location
Sutter Health
  • Book Appointment
  • Find Doctors
  • Find Locations
  • Treatments & Services
    • Book Appointment
    • Find Doctors
    • Find Locations
    • Treatments & Services
    • COVID-19 Resources
    • Pay a Bill
    • Symptom Checker
    • Get Care Today
    • Health & Wellness
    • Classes & Events
    • Research & Clinical Trials
    • For Patients
    • About Sutter Health
    • Giving
    • Volunteering
    • Careers
    • News
    • For Medical Professionals
    • Other Business Services
Close Search
  • Home
  • Ask an Expert
  • How Long Does Sunscreen Last?
Content

Ask An Expert

How Long Does Sunscreen Last?

Jane Varner

Jane Varner, M.D.

Palo Alto Medical Foundation

Question:

My son is in school all day, then jumps into a car to travel to an outdoor swim practice. He has about five minutes to get ready. If we apply sunscreen in the morning, is it still effective eight hours later? What sunscreens are best for his situation?

Answer:

I'm SO glad that your family is remembering sunscreen! The most recent statistics from the Center for Disease Control (CDC) show that approximately 70,000 people in the United States are diagnosed with melanoma each year, resulting in nearly 30,000 deaths. The biggest risk factor for developing melanoma is sun exposure.

There are two types of harmful ultraviolet (UV) rays: UVA and UVB. The UVA rays are thought to penetrate the deeper layers of the skin, causing premature aging and wrinkling. UVA rays can even penetrate window glass! The UVB rays are thought of as the "burning" rays. Broad spectrum sunscreens and sun blocks protect against both UVA and UVB rays, so be sure to look for these. Use a sunscreen or sun block with a minimum of SPF 30.

Sunscreen or sun block needs to be re-applied at least every two hours, more often if you are sweating heavily or spending time in the water. So ideally your son should reapply sunscreen just before the swim practice.

If you are spending time in the water, choose a sunscreen that is either water resistant or very water resistant (it turns out there is no such thing as water proof!). A water resistant sunscreen should be reapplied every 40 minutes and a very water resistant sunscreen should be reapplied at least every 80 minutes. You will need at least one ounce to sufficiently cover the whole body. Spray sunscreens are okay too, but make sure that the sunscreen is actually landing on the skin and not getting carried away by the wind!

Think about sun protection, regardless of cloudy skies. It is estimated that 80 percent of harmful UV rays pass through even the thickest clouds. Also remember that certain medications increase your sensitivity to the sun's rays — be sure to check with your doctor or pharmacist if you aren't sure.

Back to the threat of melanoma, the American Academy of Dermatology recommends that everyone "check their birthday suit on their birthday." At least once a year, with the help of a mirror, thoroughly examine your skin using the "ABCD" criteria:

Asymmetry: One half of the mole looks different from the other half.
Border irregularity: The edges are ruffled and uneven.
Color: The color is uneven, with dark brown and even black segments present.
Diameter: Larger than 6mm, or about the size of a pencil eraser.

If you are worried about the appearance of a mole, be sure to consult with your family doctor and/or dermatologist…it's always better to be safe!

Related Questions

Question
  • Treating Swimmer's Ear
    What is "swimmer's ear" and what is the best way to deal with it?
  • What is a Nurse Practitioner?
    My ob-gyn doctor's office recently added a nurse practitioner. Can you tell me more about their qualifications and what they do?
  • Toddler Only Wants Cereal
    My 2 1/2 year old was once a great eater, but now wants to eat only cereal - plain Cheerios to be exact. He won't eat any dinner but complains he's hungry before bed, so I let him have some cereal. How do I break the cycle?
  • The Best Sunscreen?
    I just read information about sun protection, noting the ingredients necessary for a good sun screen. I checked the sunscreens I use and see NONE of those ingredients. Can you recommend a product with the best ingredients?
  • Seborrheic Keratoses Treatment Options
    I'm 75 and have keratosis on my face and upper torso. My PCP is sometimes reluctant to take care of them using LN2, since Medicare regards this as cosmetic. Does the wart remover "Freeze Away" work sufficiently or is there a better product?

Back to Cancer

The Sutter Health Network of Care
Expertise to fit your needs
Primary Care

Check-ups, screenings and sick visits for adults and children.

Specialty Care

Expertise and advanced technologies in all areas of medicine.

Emergency Care

For serious accidents, injuries and conditions that require immediate medical care.

Urgent Care

After-hours, weekend and holiday services.

Walk-In Care

Convenient walk-in care clinics for your non-urgent health needs.

  • Contact Us
  • Find Doctors
  • Find Locations
  • Book Appointment
  • Request Medical Records
  • Donate Now
Sign in to My Health Online

Billing and Insurance

  • Pay a Bill
  • Accepted Health Plans
  • Estimate Costs
  • Medicare Advantage

About Sutter

  • About Our Network
  • Community Benefit
  • Annual Report
  • News and Media

Our Team

  • For Employees
  • For Medical Professionals
  • For Vendors
  • For Volunteers

Careers

  • Jobs at Sutter
  • Physician Jobs
  • Graduate Medical Education

Copyright © 2023 Sutter Health. All rights reserved. Sutter Health is a registered trademark of Sutter Health ®, Reg. U.S. Patent & Trademark office.

  • ADA Accessibility
  • Privacy
  • Do Not Sell My Personal Information
  • LinkedIn Opens new window
  • YouTube Opens new window
  • Facebook Opens new window
  • Twitter Opens new window
  • Instagram Opens new window
  • Glassdoor Opens new window

Cookie Policy

We use cookies to give you the best possible user experience. By continuing to use the site, you agree to the use of cookies. Privacy Policy Cookie Preferences

Privacy Policy Cookie Preferences