If you’ve ever gotten a whiff of your armpits and thought your body odor smells suspiciously like onions, you’re not alone. Even though onion-like odor is surprisingly common, it can lead to feelings of insecurity, embarrassment, or even isolation — but it doesn’t have to! Not only is this kind of scent completely normal, but it’s also almost always solvable with the right dermatologist-approved routine.
That’s where we come in! The trusted sweat experts at Ban are here to help shed some light on the science behind onion body odor causes and share the easy fixes that actually work. With a better understanding of the problem, some simple hygiene tweaks, and the right gentle daily care products, that disconcerting scent will be a thing of the past.
What Does "Smelling Like Onions" Actually Mean?
If you’re asking “why does my sweat smell like onions?” you might be surprised to learn that sweat isn’t actually what you’re smelling. Sweat itself is an odorless moisture excreted through your skin’s pores, and the unpleasant scent you’re noticing is caused by microbes on the surface of your skin metabolizing the compounds in your sweat and producing odors.
That specific onion or sulfur smell points to the presence of thiols. Thiols, or thioalcohols, are organic compounds that contain a sulfur atom instead of the oxygen atom that other alcohol compounds have. These odorous compounds are found in many things that are considered “stinky,” like onions or the scent skunks secrete. When the bacteria on your skin metabolize your sweat, they can break down sulfur-containing molecules with enzymes and produce these thiols and, with them, that signature funky smell.
7 Reasons You Smell Like Onions
There are a few reasons you may notice a sulfur smell body odor coming from your armpits, groin, or other areas.
Sulfur compounds in your sweat: As mentioned, your sweat itself isn’t smelly. However, when sweat from your apocrine glands contains compounds with sulfur in them that are metabolized by the bacteria on your skin, thiols are produced and evaporate, causing the pungent scent.
What you ate: Certain foods release sulfurous compounds when broken down in your body, and increase the potential for body odor. These include cruciferous veggies like broccoli and cabbage, alliums like garlic and onions, red meats, and alcohol.
Hormonal changes: Because only apocrine glands (attached to hair follicles) produce the sweat that tends to smell, children generally don’t experience body odor until puberty, and males tend to have more body odor than females. However, women may experience more body odor surrounding ovulation, menstruation, or menopause due to increased sweating and hormonal changes.
Stress sweat vs. heat sweat: Humans have two kinds of sweat glands: Eccrine, which cover most of your body and secrete sweat directly to the surface of your skin to cool you down, and apocrine, which open up to your hair follicles, mostly in your armpits and groin. It’s the latter that house bacteria that make you smell, so if you’ve been wondering “Why do my armpits smell like onions?,” that’s why.
Hygiene habits: Excess body odor may be a sign that you’re not washing your armpits or groin thoroughly enough to keep bacteria under control, or that the fabrics you’re choosing are trapping heat or sweat and allowing bacteria to flourish.
Medical conditions: While some body odor is normal, excessive scent can be a sign of a medical condition like trimethylaminuria (a.k.a. "fish odor syndrome"), diabetes, gout, or kidney and liver issues. If you notice an odor that smells fishy, fruity, or bleach-like, check with your doctor.
Your deodorant or antiperspirant isn't working hard enough: You may be using a deodorant that simply tries to mask odor. Ideally, the best types of deodorants will actively work to change the pH of your skin so it’s less hospitable to bacteria. Antiperspirants can also help by sealing off pores to prevent sweat in the first place. Learn more about deodorant vs. antiperspirant, here.
How to Get Rid of Onion-Smelling Body Odor
Now that you know what actually causes the scent that’s been bothering you, you’re ready to learn how to get rid of onion smelling body odor once and for all. Here are some practical steps you can take:
Switch Up Your Shower Routine
If the scent is being caused by a buildup of bacteria, you can combat it by simply showering more, focusing extra on areas like your armpits, groin, and feet, and using an antibacterial body wash. Using antiperspirant immediately after a shower on dry skin will also help.
Switch to a Clinical-Strength Antiperspirant Vs. Deodorant
Deodorants work to make your pH less inviting to bacteria and to mask foul smells created by them, but it’s possible you need a little more support. A clinical-strength antiperspirant like Ban’s Unscented Roll-On Antiperspirant will actually prevent sweat, cutting off the compounds bacteria will metabolize and stopping the stink before it starts to help you smell fresh all day.
Wearing Breathable Fabrics
Your wardrobe may be contributing to your body odor more than you would expect. Wearing clothes that are synthetic can trap heat and moisture, letting bacteria grow wild. Opting for clean clothing with breathable natural fabrics like cotton, merino wool, and linen, will wick away moisture, dry quickly, and let your skin breathe. To help even more, using products like Ban’s Private Parts Stay Dry Deodorizing Lotion will keep your sensitive areas fresh and dry all day.
Diet Adjustments
To find out if your diet is contributing to your unwanted body odor, try cutting out sulfur-heavy foods for a few weeks to see if that helps. Skip foods like cruciferous veggies, garlic, onions, red meat, and alcohol, and then slowly add them back in one at a time while taking notes on how they affect your scent.
Focus on Hydration and Stress Management
Your physical health may be impacting your smell, and decreasing stress while staying hydrated may help relieve your body odor. Drinking more water can even decrease your body temperature and prevent unnecessary sweating, while replacing water lost when you sweat.
When to See A Dermatologist or Doctor
While sweat is a normal part of being a human, there are some red flags that may demand a visit to the doctor or dermatologist. First, if you’re sweating too much, you may suffer from hyperhidrosis, which can exist on its own or be related to another medical problem. While anyone can experience body odor, noticing scents of bleach, fruitiness, or fishiness can be signs of other medical concerns, so call your doctor if you notice any of these.
When Onion Body Odor Is a Sign of Something More
Body odor is nothing to be ashamed of, but it can be a way for your body to alert you that something is going on. If you’re asking “why does my body smell like onions all of a sudden?” when it never has before, and you’ve tried all of our above tips with no luck, it may be time to talk to a doctor. Other red flags include:
Sudden onset of body odor, especially if it smells fishy, fruity, or bleach-like
An extreme increase in sweat
Persistent smell despite hygiene changes
Other unusual symptoms, like bad breath or strong-smelling urine
These may be symptoms of an uncommon metabolic disorder called Trimethylaminuria (TMAU or fish odor syndrome), and these concerns should be brought to a doctor.
FAQs
Why do I smell like onions even after I shower?
If you still smell like onions immediately after a shower, you should try using an antibacterial body wash focused on your armpits and groin, then apply a clinical-strength antiperspirant and deodorant to armpits and total-body lotion to private parts on dry skin immediately after you bathe.
Why do my armpits smell like onions but I use deodorant?
Your deodorant may not be strong enough, or you may need to use a clinical-strength antiperspirant instead. Try a product that offers both plus a light pleasant scent, like Ban’s Powder Fresh Roll-On Antiperspirant.
Can my diet really make me smell like onions?
A sulfur-rich diet can absolutely cause that onion smell, as it will add sulfur compounds to your sweat, which produce smelly thiols when metabolized by the bacteria on your skin.
Is onion body odor a sign of a health problem?
Onion body odor is generally not concerning, like fishy, fruity, or bleachy body odor. However, if it persists despite hygiene and diet changes, it may be worth a chat with your doctor.
Does onion body odor go away?
Onion body odor is not permanent, and can usually be managed with hygiene changes, diet changes, and an effective total body antiperspirant and deodorant routine.
Key Takeaways
If you’re struggling with oniony body odor, it’s important to know that it’s totally normal and totally solvable. Take some time to reassess your hygiene routine, decrease your stress, reevaluate your diet, and find a whole-body antiperspirant regimen that fits your needs and lifestyle. Ban’s science-backed, dermatologist-developed line of targeted sweat care solutions is the perfect place to start, and with these tips, you’ll be feeling fresh and confident all day long in no time!