Secret Shopper: Which natural insect repellent ingredients are best?

NFM Secret Shopper: I want to use a natural insect repellent this summer. Which ingredients are safe and effective?

Store: We have plenty of options, but certain essential oils seem to be best. Geranium oil works really well against ticks, and oil of lemon eucalyptus is very good for mosquito protection. There are others you can try, such as lavender and citronella. It kind of depends on which scents you like.

NFM: So essential oils are the way to go? And they’re all safe?

Store: As long as you don’t squirt them directly into your eyes, then yes, they’re all safe. And yes, essential oils are more potent than other natural ingredients so they work better.

How did this retailer do?

Our expert educator: Jennifer Sass, senior scientist at the Natural Resources Defense Council

I like that the retailer recommended oil of lemon eucalyptus. Even the Environmental Protection Agency deems this ingredient effective. I’ve had success with other essential oil–based repellents as well. But it’s important to know that these oils trigger allergies in some people, and it’s unclear how effective some of them are as repellents. Peppermint, cinnamon, lemongrass, cedarwood and rosemary are examples. That said, just as this salesperson suggested, it’s not so much which essential oil is good or bad; it’s more about trying out different formulations and seeing what works for you. For example, peppermint oil makes my skin break out while lemongrass oil does not—and it seems to keep mosquitos away.

Aside from allergies, essential oils are generally safe, as the retailer mentioned. However, tea tree and lavender oils can be endocrine disruptors, so they should be used sparingly. Pregnant women should avoid these two altogether.

Finally, natural repellents aren’t as strong and don’t tend to last as long as chemical repellents, so if you’re going deep into the woods, you might want something stronger such as DEET. You can spray it onto your clothes instead of your skin to minimize direct contact. But if you’re just sitting on your porch above the grass, a natural repellent is probably fine.