Body odor happens when bacteria on your skin break down compounds in sweat into smaller, volatile chemicals that smell. The good news: because odor is driven by bacteria rather than sweat itself, you have several effective ways to interrupt that process. What works best depends on whether the issue is everyday underarm odor, hormone-related changes, or something originating from a different part of the body entirely.
Why Body Odor Happens
Sweat on its own is virtually odorless. The smell starts when specific bacteria, primarily Staphylococcus hominis and Staphylococcus epidermidis, feed on the proteins, fatty acids, and lipids in your sweat. They convert these into smaller molecules: isovaleric acid (a sour, cheesy smell), acetic acid (vinegar-like), and sulfur compounds that produce that classic “B.O.” edge. The more of these bacteria present, the stronger the odor.
Your underarms are the primary hotspot because they concentrate apocrine glands, which produce a thicker secretion rich in proteins and lipids. But the groin, feet, and skin folds under the breasts also harbor the warm, moist conditions these bacteria love.
How Hormones Affect Your Scent
If you’ve noticed your body odor shifting throughout your menstrual cycle, you’re not imagining it. Estrogen promotes blood flow to the skin and increases your tendency to sweat, while progesterone does the opposite. During the late follicular phase, right before ovulation, estrogen is high and progesterone is low, which changes both how much you sweat and the composition of what’s on your skin. Research published in Proceedings of the Royal Society B found that body odor collected during this phase was consistently rated as more pleasant than odor from other cycle phases.
Perimenopause and menopause bring a different challenge. Fluctuating and declining estrogen levels trigger hot flashes and night sweats, increasing the volume of moisture on your skin and giving bacteria more to work with. Pregnancy similarly shifts your hormonal baseline, and many women report stronger body odor during the first trimester.
Daily Hygiene Strategies That Work
The most effective approach targets bacteria directly. Washing your underarms, groin, and skin folds with an antibacterial soap once or twice daily removes the bacterial colonies responsible for odor. Pay special attention to these areas rather than relying on a general lather. After washing, dry thoroughly. Bacteria multiply fastest in damp environments, so leaving moisture in skin folds works against you.
Shaving or trimming underarm hair can also help. Hair traps moisture and provides surface area for bacteria to cling to, which is why odor tends to be stronger when hair is longer.
Lowering Skin pH
Your skin’s natural pH sits between 4.0 and 6.8, but the underarm area tends to be closer to neutral, especially after sweating. Odor-causing bacteria thrive at higher pH levels. Applying a glycolic acid product (a common skincare ingredient) to clean, dry underarms lowers the pH and creates an environment where these bacteria struggle to grow. It won’t reduce sweating, but it can significantly cut odor between showers. A 5-10% glycolic acid toner or serum applied in the morning works for many people. Start every other day to make sure your skin tolerates it.
Choosing the Right Deodorant or Antiperspirant
Deodorants and antiperspirants do different things. Deodorants mask or neutralize odor. Antiperspirants use aluminum-based compounds to temporarily block sweat ducts, reducing the moisture bacteria need. Many products combine both.
If over-the-counter options aren’t enough, prescription-strength antiperspirants contain higher concentrations of aluminum chloride. Brands like Drysol and Xerac AC are available through a dermatologist and are typically applied at night when sweat glands are less active, allowing the active ingredient to form a more effective plug.
Aluminum-Free Options
If you prefer to skip aluminum, look for ingredients with actual evidence behind them. Hop extract, derived from the same plant used in brewing, has strong antimicrobial effects against the specific bacteria that cause underarm odor. In testing, it dropped malodor scores from above 6 (on a scale where higher means worse) down to about 1.8 after eight hours, and held near that level through 24 hours. Tannin-rich plant extracts work through a similar mechanism, binding to bacterial proteins and disrupting growth. Some essential oils, particularly thyme-family species, also show lab-tested antibacterial activity against S. epidermidis at low concentrations.
One newer ingredient worth knowing about is a synthetic compound called polyquaternium-16, which damages bacterial cell membranes. In sensory testing by trained evaluators, it performed roughly as well as a standard 10% aluminum-based antiperspirant for odor control.
What You Eat Shows Up in Your Sweat
Certain foods increase the concentration of odor-producing compounds your body excretes through sweat. Sulfur-rich vegetables like broccoli, cabbage, cauliflower, and Brussels sprouts are common culprits. Eggs, liver, and seafood are high in trimethylamine, a chemical your body normally breaks down but that can accumulate and produce a strong, fishy smell in sweat, breath, and urine.
For most people, these foods cause only a mild, temporary shift. But if you notice a persistent strong odor that doesn’t respond to hygiene changes, it may be worth reducing intake of these foods for two to three weeks to see if things improve. A small number of people have a genetic condition called trimethylaminuria that impairs their ability to process trimethylamine, making dietary management especially important.
Garlic, onions, and heavy alcohol consumption also contribute to odor through compounds that are metabolized in the gut, enter the bloodstream, and exit through sweat glands.
Your Clothes Matter More Than You Think
Polyester and other synthetic fabrics are hydrophobic, meaning they repel water but attract the oily compounds bacteria feed on. Research on bacterial adhesion found that S. hominis and S. epidermidis, two of the primary odor-causing species, adhere significantly better to polyester than to cotton. This is why a polyester workout shirt can smell terrible after one use while a cotton tee stays relatively neutral.
Switching to natural fibers like cotton, linen, or merino wool for clothing worn close to the body can make a noticeable difference. If you prefer synthetic athletic wear, wash it promptly after use and consider a sports-specific detergent designed to break down the oily residues that trap bacteria in synthetic fibers. Letting sweaty clothes sit in a hamper for days allows bacterial colonies to become deeply embedded in the fabric.
Vaginal Odor Is a Separate Issue
Many women searching for help with body odor are actually noticing a change in vaginal scent, and it’s important to understand these are two different things. Normal vaginal secretions have little to no odor, or a mild, slightly tangy smell. A strong fishy odor is the hallmark of bacterial vaginosis, the most common vaginal infection, caused by an overgrowth of bacteria like Gardnerella vaginalis that produce volatile amines.
What makes this tricky is that odor from the groin area can be hard to pinpoint. Sweat from the apocrine glands around the vulva, odor from the anal area, and actual vaginal discharge can all blend together. If you notice a distinctly fishy or foul smell that persists after bathing, or if it comes with unusual discharge, that points toward an infection rather than a hygiene issue. Douching or using scented products internally will make the problem worse by disrupting the vaginal microbiome.
When Odor Persists Despite Everything
Body odor that doesn’t improve with consistent hygiene, dietary changes, and effective products sometimes has a systemic cause. Your gut bacteria, liver function, and kidney function all influence what odor-producing compounds end up in your sweat. Conditions like diabetes can change your body’s scent profile, and certain medications alter sweat composition.
Excessive sweating itself, called hyperhidrosis, amplifies odor simply by providing more raw material for bacteria. If you soak through shirts regularly regardless of temperature or activity, a dermatologist can assess whether prescription treatments are appropriate. Options range from stronger topical products to procedures that target the sweat glands directly.