Here's Why You Might Have Smelly Sweat

Wondering, "Why does my sweat smell so bad?" From your birth control to your eating habits, there are lots of reasons why your sweat might smell.

If you think your roommate's lack of deodorant use is highly questionable, know this: Some people actually don't have smelly sweat. If you're not one of the lucky ones, the good news is that you have more control over that ~odor~ than you think. As it turns out, your armpits don't smell because of the sweat itself, but rather it's the bacteria on your skin mixing with your perspiration that causes the sweat to smell — and certain factors can lead to the resulting aroma smelling, well, really bad.

Here are nine possible answers to the age-old question of "why does my sweat smell so bad?" Just remember this before you spend too much time trying to squash the smell: Sweat and smelly armpits are just a fact of life — even more so if you're an active human being. Go easy on your body; it's just doing its job.


If just imagining, say, a blind date makes you sweat, you're not alone. A majority of people report breaking out into a nervous sweat when confronted with something stressful — and anxiety activates the hormone cortisol in your body, which in turn kicks your sweat glands into high gear. The sweat then gets trapped in your leggings or tank, combines with bacteria, and suddenly you have smelly sweat on your hands. (

Certain Clothes

Natural fibers including cotton, wool, and linen soak up sweat from your skin and allow it to evaporate. But while synthetic fibers including rayon, polyester, nylon, and even some natural fibers such as silk look pretty, their ability to repel water and sweat will make your sweat smell worse in the end. Instead of helping move the sweat away from your skin's bacteria, these fabrics keep it trapped on the surface.

Your Deodorant

A catch-22 of modern hygiene is that the stuff you buy to help keep your armpit smell away may actually be making the problem worse. Ingredients in some antiperspirants, deodorants, body washes, body sprays, and lotions can encourage smelly sweat by giving bacteria more food. Many doctors now advise patients with body odor problems to wash with antibacterial soap or to consider bathing less frequently. If you're still left smelling, doctors also suggest spritzing your pits with lemon juice or apple cider vinegar diluted with water — the acid will inhibit bacterial growth, the real source of the stench.


Still haven't found the answer to why your sweat smells so bad? If it's a sudden change, it could be a new prescription. Many medications have increased sweating or body odor as a known side effect. This includes over-the-counter pain relievers and allergy medications, as well as prescription meds including some anti-depressants, ADHD meds, and even birth control pills.

Nutrient Deficiencies

Eating tons of garlic can make you smell like an Italian restaurant at the gym the next day, but what you don't eat can also affect your body odor. Research has found that people who are deficient in magnesium, a vital nutrient found in leafy greens and nuts, had stronger body odor than people who got enough. Who knew that eating a sweet treat (dark chocolate is a great source of magnesium) could also make you smell sweet? (See: The Benefits of Magnesium and How to Get More of It In Your Diet)


Bacteria love sweets, so eating too much sugar can cause an overgrowth of yeast on your skin, which in turn converts those sugars into alcohols that cause you to smell anything but sweet, according to Edward Group, a certified clinical nutritionist. But remember that having sweet treats in moderation is nothing to be frowned upon.

Your Bathroom Habits

Holding in your waste will not only make you rush for the bathroom but can also make you smell like one. Research has found that in cases of severe constipation, toxins released by the digestive system may seep through the pores, giving you what's affectionately known as "fecal body odor." Oof. In addition, the "ammonia" smell from a urinary tract infection can become so concentrated that the odor comes out through your pores as well.

Fried Food

Anyone who's done a long treadmill run the day after hitting their fave Mexican restaurant knows that foods such as onions, garlic, or other strong foods or spices can make your sweat pretty fragrant, but your fried food cravings may be equally to blame. Apparently, the fats and oils in fried and baked goods can become rancid in your body, causing poor digestion and, consequently, body odor.

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