How long does mosquito repellent last once it is on your skin, and how long does the bottle itself stay good in the cupboard? They are two different questions, and the answers come from different places. The first has real published figures behind it: university extension services and the US National Pesticide Information Center state protection windows for every registered active ingredient. The second is murkier, because most bottles say nothing about expiry at all. Here is what the regulators and the scientists actually put in writing, and the honest gaps they leave.
How long does mosquito repellent last? The published windows
The clearest single reference is Penn State Extension's tick and mosquito repellent guide, which tabulates a "duration of effectiveness" for each EPA-registered active. In that table, DEET products run 2 to 8 hours, picaridin 3 to 10 hours, IR3535 sits at 4 to 6 hours, and oil of lemon eucalyptus at 2 to 5 hours (Penn State Extension, Tick and Mosquito Repellent Guide, reviewed 10 May 2022). Those are ranges, not promises, and the spread inside each one tells you something important: the number on any given bottle depends on the concentration inside it.
NPIC's fact sheet explains the shape of that spread in two sentences worth memorising: "Higher concentration repellents may protect people for longer. However, they are not better at keeping insects away" (NPIC, Insect Repellents Fact Sheet, reviewed February 2018). In other words, a stronger bottle buys you time, not a tighter shield. The same sheet warns that "repellents with less than 10% of an active ingredient may only offer protection for short periods of time (1-2 hours)," and adds a ceiling from the other direction: products with more than 50% DEET offer no extra protection. The CDC's position, as NPIC records it, is to choose products with DEET concentrations of 20% or more if you go the DEET route.
So the honest answer to the question is a two-step check: find the active ingredient, then find its percentage. The two together, not the marketing on the front, tell you roughly which window you are in. If you are weighing the two most common synthetics against each other, our side by side look at picaridin versus DEET on your skin goes deeper on what separates them beyond the clock.
What shortens the clock in real life
The published windows are measured under controlled conditions, and your afternoon is not a controlled condition. NPIC is direct about the three things that eat into the numbers: "Sweat, water contact, and rubbing from clothing can affect how long a repellent may be effective." That is why water resistant formulations exist as a separate shelf category, and why the label instruction to reapply is not a suggestion but part of how the product was tested. NPIC's practical advice is to "follow label directions to find out how long to wait before reapplying," because that interval is the manufacturer's own tested figure for that specific formula.
Application quality matters just as much as time. The EPA's guidance is to apply repellents only to exposed skin and clothing, never under clothing, and to spray into your hands first before applying to the face rather than misting straight at it (EPA, Using Insect Repellents Safely and Effectively, last updated 10 November 2025). A thin, patchy coat at hour zero behaves like a short window whatever the concentration says. And when the day ends, the EPA recommends washing treated skin and clothing with soap and water once you are back indoors, so whatever film you chose in the morning should be one you are happy to remove at night.
There is one more timer most people never think about: the combination bottle. NPIC records the CDC's position that combined sunscreen and repellent products are not recommended, partly because "sunscreen may need to be used more often than a repellent." Two products on two different clocks, fused into one layer, means one of them is always being applied at the wrong interval. If your routine pairs the two, the sunscreen and insect repellent order is its own question, and we have walked through it separately.
Protection time as a way of shopping
The EPA builds duration into its own product search as a first-class filter, which is telling in itself. Its product search tool lets you filter registered repellents by, among other things, "protection time," and its own advice is to ask how long you will be exposed and to "use a product with a protection time that fits your activity" (EPA, Find the Repellent Right for You, last updated 8 September 2026). The agency also adds a caveat that keeps everyone honest: even for registered products, "there are variations in the resulting protection times because of differences in the testing conditions."
Read together with the Penn State table, that gives you a sane mental model. The range for your active is the outer boundary. Your behaviour, the weather, and your clothing decide where inside that range your day actually lands.
Does mosquito repellent expire?
Here is where the label goes quiet. Repellent bottles commonly carry no expiry date at all, so the practical question becomes: what do the people who regulate pesticides say about ageing stock?
The NPIC's storage guidance is the closest thing to an official answer (NPIC, Storage of Pesticides, last updated 6 January 2026). Three points from it do most of the work. First, the container: pesticides should stay in their original containers, which are "designed to protect the product" and made of materials that withstand the chemicals inside. Second, the temperature: "extremes in temperature can change the chemistry of some pesticides inside the container," and as a general rule NPIC suggests storage between 40 and 90 degrees Fahrenheit (roughly 4 to 32 degrees Celsius). Third, and most quotable for anyone staring at a dusty bottle from three summers ago: "buy only what you need this season."
That last line is the regulators' quiet answer to the expiry question. They do not promise a repellent stays good forever, and they do not print a date. They tell you to keep the chemistry stable, keep the container sealed, and not to stockpile. A bottle that has lived through two years of hot sheds and frozen car boots has had its chemistry challenged in exactly the way NPIC warns about, whatever the liquid still looks like. If the contents have separated, changed colour or smell, or the spray mechanism has failed, the sensible move is to replace rather than trust it, and to dispose of the old one properly rather than pouring it anywhere.
Where a daily skincare cream fits this picture
The duration figures above are the ones published for registered actives. Misaj, a Paris based skincare brand, makes a daily skincare cream. On its product page, as of 12 October 2026, the brand describes Glow Protect as combining "hydration, skin barrier support and botanical mosquito protection in a single cream designed to be worn daily," with eucalyptus citriodora, geranium, Atlas cedar and clove forming what it calls "a natural aromatic blend that helps deter mosquitoes."
The full ingredient list is published on the Glow Protect product page if you want to read it the way this article has been reading labels.
The takeaway worth keeping
The window comes from the active ingredient and its concentration, and the published ranges run from roughly 1 to 2 hours at the weak end to 10 hours for strong picaridin. Sweat, water and clothing pull you toward the bottom of your range; even application and timely reapplication keep you near the top. And the bottle in the cupboard has no promised lifespan, only the regulators' storage logic: original container, moderate temperature, and only what you need this season. A repellent strategy built on those four facts will outlast any single product claim.
Frequently asked questions
How long does mosquito repellent last on skin?
It depends on the active ingredient and its concentration. Penn State Extension's table puts DEET at 2 to 8 hours, picaridin at 3 to 10, IR3535 at 4 to 6 and oil of lemon eucalyptus at 2 to 5. NPIC adds that anything under 10% active may only protect for 1 to 2 hours.
Does a higher percentage repel mosquitoes better?
No. NPIC states that higher concentration products may protect for longer but are not better at keeping insects away, and that products above 50% DEET offer no extra protection. Concentration buys time on the clock, not a stronger effect.
Does mosquito repellent expire?
Bottles commonly carry no expiry date. NPIC's storage guidance is the practical answer: keep the product in its original container, avoid temperature extremes (40 to 90 degrees Fahrenheit as a general rule), and "buy only what you need this season." Separated, discoloured or odd-smelling contents are a reason to replace.
Can I use a combined sunscreen and repellent to save time?
The CDC does not recommend combination products, and NPIC records why: sunscreen may need to be used more often than a repellent, so one shared layer puts one of the two on the wrong schedule. Apply them as separate steps instead.
Sources (every one fetched 2026-10-05)
- Penn State Extension, Tick and Mosquito Repellent Guide, reviewed 10 May 2022 (duration-of-effectiveness table: DEET 2-8 h, picaridin 3-10 h, IR3535 4-6 h, oil of lemon eucalyptus 2-5 h). https://extension.psu.edu/tick-and-mosquito-repellent-guide
- NPIC, Insect Repellents Fact Sheet, review date February 2018 (concentration buys time not strength; under 10% active means 1-2 hours; over 50% DEET adds nothing; sweat, water contact and rubbing from clothing shorten effectiveness; follow label directions for reapplication; CDC's position against combination sunscreen-repellent products). https://npic.orst.edu/factsheets/repellents.html
- EPA, Using Insect Repellents Safely and Effectively, last updated 10 November 2025 (exposed skin and clothing only, never under clothing; spray into hands first for facial application; wash treated skin and clothing after returning indoors). https://www.epa.gov/insect-repellents/using-insect-repellents-safely-and-effectively
- EPA, Find the Repellent Right for You, last updated 8 September 2026 (protection time as a search filter and a shopping criterion; testing-condition variation caveat). https://www.epa.gov/insect-repellents/find-repellent-right-you
- NPIC, Storage of Pesticides, last updated 6 January 2026 (original containers; temperature extremes change pesticide chemistry; 40-90°F general storage rule; "buy only what you need this season"). https://npic.orst.edu/health/storage.html
- misajskin.com, Glow Protect product page (brand wording quoted verbatim, checked 12 October 2026). https://misajskin.com/products/glow-protect