Sounds like a miracle, right? They are in many ways, but SPF drops aren't without their caveats. When using a mixable product, consumers have a tendency to use a few drops and call it a day. "In order for the booster to be effective, you must use enough of it," says dermatologist Joshua Zeichner, MD. "The same rule applies to a booster as does any other sunscreen. You need one nickel-sized amount applied to the full face."
And another thing: You can't really mix them with anything. "I caution against combining them with specialized moisturizers that contain ingredients like antioxidants or hydroxy acids as these ingredients may interact with the sunscreens," Dr. Zeichner adds. He recommends combining sunscreen drops with simple moisturizers.
Dermatologist Dendy Engelman, MD, agrees. "I would advise mixing drops with a cream moisturizer or liquid foundation and to avoid oil-based products that could break down the integrity of the product," she says. "Since most sunscreen drops contain vitamin C, this should not be used in conjunction with retinol because when used together, the skin can become more vulnerable and irritated."
Ahead, the best sunscreen drops to try this season.