How to Read an Insect Repellent Label

Turn over a bottle of repellent and you will find the real product. The front says what the maker would like you to remember, usually a freshness, a number of hours or a leaf. The back says what the product is, what is in it and how it is meant to be used. Reading the back takes about a minute, and it is the best minute you can spend in the pharmacy aisle.

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Start with the registration number

EPA runs a registration system for skin-applied repellents. Look for "EPA Reg. No." on the label. EPA explains that the number means the company provided the agency with technical information on the product's safety and its effectiveness against mosquitoes, ticks or both. CDC recommends choosing registered products, and EPA's repellent search tool lets you filter by pest, protection time and active ingredient, or check a number you already have.

The flip side is worth knowing. A bottle with no registration number is not an EPA-registered repellent, however natural or pleasant it smells. That includes essential oils, ours among them. We sell a steam-distilled lemon eucalyptus essential oil for its fragrance, and it carries no repellent registration, so it sits in a different category from the products described here.

The active ingredient line

This is where products really differ. CDC's six active ingredients for registered repellents are DEET, picaridin, IR3535, oil of lemon eucalyptus (OLE), para-menthane-diol (PMD) and 2-undecanone. The percentage next to the name tells you how much of the product it is, and it matters because protection time rises with concentration, up to a point. The American Academy of Pediatrics gives helpful examples: about 2 hours from 10 percent DEET and about 5 hours from 30 percent, with no extra protection beyond 50 percent; 3 to 4 hours from 5 percent picaridin and 8 to 12 hours from 20 percent; and, for OLE, up to 2 hours at 8 to 10 percent versus around 6 hours at 30 to 40 percent. CDC's Yellow Book adds that products with less than 10 percent active ingredient might offer only limited protection, often 1 to 2 hours.

Comparing across ingredients takes care, because the same number can mean different things on different bottles. A 30 percent DEET product and a 30 percent OLE product are not the same strength of the same thing, so compare within an ingredient first, then across them using the stated protection times. Our concentration guide goes into the OLE side in more depth.

The rest of the label, in the order you will use it

The claim. Does it name mosquitoes, ticks or both? Check which pests the label names, since that is what the maker is claiming. EPA's voluntary repellency graphic, where present, shows the pests and protection times, and EPA notes that it is available only for qualifying products.
Directions. Where to apply and how often. EPA stresses that reapplying as the label says is part of how the product works.
Age statements. This is where OLE and PMD labels need a careful look. CDC and AAP say not to use them on children under 3, and EPA notes that some labels carry that restriction while certain OLE-only products at 30 percent or less do not. Follow the label and ask your pediatrician.
Precautions. Flammability warnings, keep out of eyes, do not apply over cuts, store out of children's reach.
First aid and storage. Keep the container handy if you ever need to call Poison Help (1-800-222-1222, as AAP lists it).

Colors, pictures of leaves and bold slogans are there to catch your eye. The small print is there to inform you. Spend your time on the small print.

A word on "natural" and "pure" on the front

Words like natural, plant-based or pure are marketing, not registration. AAP points out that "natural" repellent ingredients such as citronella, geranium and peppermint have not been approved for effectiveness by EPA and mostly keep insects away for only a short time, and that "pure" oil of lemon eucalyptus products have not been tested for safety as insect repellents. That is a useful reminder that the registration number and the active ingredient line tell you more than any adjective. If you are choosing between registered options, our piece on choosing a lemon eucalyptus repellent and the ingredient comparison are good next stops.

Do it at home, not in the aisle

Label reading is much easier at the kitchen table than in a busy store with a restless child. If you can, look up the products you are considering ahead of time, jot down the names of the active ingredients you want to compare, and take the list with you. When you are in the aisle, you will only need to match the label to your list.

Print is small on purpose, so a phone camera helps. Take a photo of the back of the bottle, zoom in, and read the directions slowly. That photo is also handy later if you need the details again, because the label tends to wear off after a summer in a bag.

The thirty-second check

Before you buy, find the registration number, read the active ingredient and its percentage, match the protection time to your plans, and look at the age statement. After that, the directions are about habits, which our guide to putting repellent on correctly covers.

The label is the legal instruction sheet for the product in your hand, and once you know where to look, it is a quick read.