7 doctors weighed in:
Skin care: how long does sunscreen last?
7 doctors weighed in

4 doctors agree
In brief: At most 2 hours
Although the spf rating of a sunscreen tells you how effective it is during use, it is important to reapply frequently and in adequate amount.
Sunscreen should be reapplied every 2 hours to maintain efficacy, as factors such as sweating, water exposure, and physical removal can decrease its effect and lead to burns and skin cancer risk.

In brief: At most 2 hours
Although the spf rating of a sunscreen tells you how effective it is during use, it is important to reapply frequently and in adequate amount.
Sunscreen should be reapplied every 2 hours to maintain efficacy, as factors such as sweating, water exposure, and physical removal can decrease its effect and lead to burns and skin cancer risk.
Dr. Roman Bronfenbrener
Dr. Roman Bronfenbrener
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Dr. Otto Placik
Surgery - Plastics
2 doctors agree
In brief: Varies by type
This will vary according to the product as well as the activities of the individual ( sweating, exercise, bathing/swimming).
Appropriate instructions are usually provided with the product

In brief: Varies by type
This will vary according to the product as well as the activities of the individual ( sweating, exercise, bathing/swimming).
Appropriate instructions are usually provided with the product
Dr. Otto Placik
Dr. Otto Placik
Thank
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Dr. Christopher Crosby
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