Sweating, swimming and drying the skin reduce sunscreen protection.
Outdoors, sunscreen should generally be reapplied according to the label, about every two hours, and sooner after swimming or sweating. No sunscreen provides complete protection; clothing, a hat and shade remain important.
Medical principle
Skin needs protection from ultraviolet light, heat, chemicals and physical injury. New or persistent changes matter more than comparisons with online photographs; examination is needed for a definite diagnosis.
Practical steps that may help
- Combine shade, appropriate clothing, a hat and broad-spectrum sunscreen.
- Try a new skin product on a small area first and avoid combining irritating products on your own.
- Photograph moles periodically in similar light, at the same distance and angle.
When should you seek medical care?
Extensive blistering, deep or chemical burns, spreading infection, airway swelling, changing moles or a wound that does not heal need medical assessment.
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