I received an e-mail from the U.S. Food and Drug Administration Monday morning with this subject line: “Should You Put Sunscreen on Infants? Not Usually.” (There was actually no period at the end, but I couldn’t bear not to put one there.)

That surprised me. I thought we were supposed to slather sunscreen on every inch of everyone’s skin, no matter how hold or young, even when the sun’s not shining.

But it turns out the FDA would prefer that caregivers use sunscreen as a last resort, and then quite sparingly, on babies under 6 months. Instead, we’re supposed to protect infants by keeping them in the shade, covering their skin with clothing and brimmed hats – but not baseball caps.

The FDA’s consumer update notes that because babies’ skin is thinner and more permeable than that of older kids and adults, and because their skin-to-body-weight ratio is greater than that of older people, they’re more likely to absorb sunscreen ingredients and suffer allergic or inflammatory reactions to them.

If you feel you must apply sunscreen to your baby, the agency suggests using small amounts (using a product with an SPF of 15 or higher) and only “to small areas such as the cheeks and back of the hands.”

Should you choose to stick with sunscreen after all, here’s a helpful blog by former Post staffer and relatively new mom Rachel Saslow about the best sunscreens for babies.