We’ve All Been Putting on Deodorant at the Wrong Time

Like most humans (unless you work for a deodorant manufacturer or study dermatology), you’ve probably spent your entire post-pubescent life applying deodorant in the morning, amid your showering, face-washing, hair-brushing, getting-dressed routine. And as someone who has been doing exactly that her whole life, I was distressed to learn we’ve all been doing it wrong: Turns out there’s plenty of evidence to suggest the best time to apply deodorant is at night, right before you head to bed.

The difference between deodorant and antiperspirant

To clarify, this apply-at-night rule covers only deodorant containing antiperspirant. (The function of deodorant without antiperspirant is to kill or mask odor-causing bacteria, not — as anyone who’s ever used Tom’s of Maine can tell you — actually reduce how much you sweat.) Antiperspirant, on the other hand, is designed to temporarily plug your sweat pores and reduce the amount of perspiration expelled, keeping your armpits dry (and thus inhibiting odor-causing bacteria growth).

Why is night-time application better?

So, why is it more effective to apply antiperspirant deodorant at night? When you are less active (sleeping), your body temperature drops, causing you to sweat less. This lack of moisture enables your body to more readily absorb the active ingredient in most antiperspirants — aluminium — as Dr. David Pariser, president of the American Academy of Dermatology, explained to Consumer Reports. (It’s easier for the aluminium to penetrate the skin when it doesn’t have to wade through the very thing it’s working against.) Overnight, your skin will have more time to absorb the antiperspirant, making it more effective than if you apply it immediately before rushing around to get ready for the day.

Good news: Showering won’t wash it off

So what if showering in the morning is a non-negotiable for you — can you still follow this rule? Yes! Because you’ve given the antiperspirant sufficient time to penetrate and plug your sweat pores overnight, it’s not resting on the surface of the skin, leaving it susceptible to being washed off. What’s more? Most antiperspirants are made to last 24-48 hours, so depending on how much you sweat, you may not even need to apply it every day.

Should you be worried about aluminium in your deodorant?

Due to a long-held speculation on the internet that aluminium is a contributing factor to breast cancer and Alzheimer’s disease, there is an ever-growing market for “natural” deodorants that don’t contain aluminium. However, according to the Alzheimer’s Society, “multiple small and large scale studies have failed to find a convincing causal association between aluminium exposure in humans and Alzheimer’s disease.” We’ve also gone into detail to debunk the speculative association between aluminium and those health issues. (Some of you don’t care though, do you? You’re probably already down in the comments making your case.)

And a few more deodorant surprises…

In case you needed more to shake up your worldview today: Since deodorant should be applied to dry skin, guess when is not a good time to apply? Right after the shower! For best results, thoroughly rid those pits of dampness before application. Also? Deodorant can be applied anywhere you sweat. We’re not saying we’ve tried swiping it under all of our floppiest bits in the peak heat of summertime, but we’re not saying we’ll never try it. Also, the groin area (only for men; this manoeuvre is not recommended for women). You’re welcome? Honestly, we’re not sure.