Generally, it is recommended to apply sunscreen every two hours, or after swimming and sweating. This is because sunscreen can wear off or rub off over time, and it may not be as effective as when applied first.

Additionally, using a water-resistant sunscreen can help provide longer protection while swimming or sweating, but it’s still important to reapply every two hours.

It’s also important to use enough sunscreen to adequately cover the exposed skin. The general guideline is to use about 1 ounce of sunscreen for each application.

Remember to protect yourself from harmful UV rays and also add protective measures other than sunscreen. Seek shade during peak sun hours, wear protective clothing and wear a hat and sunglasses to protect your skin and eyes from harmful UV radiations.