Tanning: Does a 'base tan' prevent sunburn?

Many people go to tanning salons to get a so-called "base tan" before leaving on a beach vacation. The theory behind this is a few sessions of indoor tanning will protect your skin from sunburn. But there's little evidence that this is true.

Tanning under the sun or a sunlamp gives protection that is equivalent to a sun protection factor (SPF) of 4 or less, which translates into a little extra time in the sun before you start to burn. But the larger issue is that any change in skin color is a sign of damage from ultraviolet (UV) radiation. Repeated exposure to UV radiation — whether from the sun or a tanning bed — increases your risk of premature skin aging and skin cancer.

To prevent sunburn and other skin conditions, use these sun protection methods:

• Avoid extended sun exposure between 10 a.m. and 4 p.m. The sun's rays are much stronger during these hours.
• Cover up. Wear tightly woven clothing that covers your arms and legs and a broad-brimmed hat. Clothing specifically designed to protect from UV exposure is also available.
• Use sunscreen frequently and liberally. Apply sunscreen 30 minutes before going outdoors and reapply about every two hours.

Some people have medical conditions, such as polymorphous light eruption, that may require small, incremental exposures to UV light before a vacation to prevent flare-ups. Talk to your doctor before beginning a regimented sunbathing program if you need to treat or prevent a skin condition.