Hollywood Dermatology

It is recommended to apply sunscreen approximately 30 minutes before being in the sun so that it can be absorbed by the skin and less likely to wash off when you perspire.

How To Apply Sunscreen
Shake the sunscreen bottle well before use to mix particles that might be clumped up in the container. Be sure to apply enough sunscreen. As a rule of thumb, use a handful to cover your entire body. Use on all parts of your skin exposed to the sun, including the ears, back, shoulders, and the back of the knees and legs.

Remember to reapply sunscreen after swimming or strenuous exercise.
Apply sunscreen often throughout the day if you work outdoors, and wear hats and protective clothing.

What To Look For When You Buy Sunscreen

• Pick a broad-spectrum sunscreen that protects against UV-A and UV-B rays and has a sun protection factor (SPF) of at least 15.
• Look for a waterproof brand if you will be sweating or swimming.
• Buy a brand that does not contain para-aminobenzoic acid (PABA) if you are sensitive to that ingredient.
• Use a water-based sunscreen if you have oily skin or are prone to acne.  
• Be aware that more expensive does not mean better.Although a costly brand might feel or smell better, it is not necessarily more effective than a cheaper product.  
• Be aware of the expiration date because some sunscreen ingredients might degrade.