High altitudes mean less atmosphere to filter out UV rays. Burning occurs even on a cloudy day. Th e sun's rays can penetrate through three feet of water. Photosensitivity, an increased sensitivity to sun exposure, can occur with certain medications such as oral contraceptive pills, tetracycline products and Retin-A . Consult your physician or pharmacist before going out in the sun if you are taking any medication.
Photosensitivity also can occur with certain diseases such as lupus.
Use a sunscreen with an SPF of 15 or higher, and apply to all exposed areas. Re-apply while swimming or during prolonged periods of sweating, at least every two hours. Waterproof sunscreens are available, but also need to be re-applied during an outing. Follow product directions carefully. Individuals who work outside, fair-skinned individuals, and persons who already have had skin cancer should apply sunscreens daily.