Sweat that smells like potatoes is almost always caused by bacteria on your skin breaking down compounds in your perspiration into sulfur-containing molecules. These molecules can produce earthy, starchy, or root-vegetable-like odors that are distinct from the more common onion or vinegar smell most people associate with body odor. The good news: it’s rarely a sign of anything serious, though in some cases it points to dietary factors or health conditions worth understanding.
How Bacteria Create the Smell
Fresh sweat is nearly odorless. The smell develops when bacteria living on your skin feed on the fats, proteins, and amino acids in your perspiration and release volatile byproducts. Different bacterial species produce different smells, which is why body odor varies so much from person to person and even from one body part to another.
The two dominant bacterial groups in the armpit are Corynebacterium and Staphylococcus, which together account for roughly 75% of the underarm microbiome in most people. Corynebacterium species are particularly efficient at converting sweat compounds into strong-smelling molecules, including sulfur-based ones. In some individuals, Corynebacterium can make up over 98% of their armpit bacteria. If your personal bacterial mix skews heavily toward certain strains, the byproducts they generate can lean earthy or starchy rather than sharp or sour.
Sulfur compounds are especially relevant here. Molecules like dimethyl sulfide, which naturally occurs in foods like corn, cabbage, and asparagus, produce what researchers describe as a “decomposed vegetable” odor. When skin bacteria generate similar sulfur-based compounds from your sweat, the result can smell distinctly potato-like. Raw potatoes themselves get much of their characteristic smell from sulfur compounds and earthy chemical groups called pyrazines, so the overlap makes sense.
Why Your Diet Matters
What you eat directly influences the chemical makeup of your sweat. Sulfur-rich foods are the most common dietary trigger for vegetable-like body odor. These include garlic, onions, cruciferous vegetables (broccoli, cauliflower, cabbage), eggs, and red meat. Your body processes the sulfur in these foods and excretes some of it through your sweat glands, giving bacteria more raw material to work with.
High-starch diets can also play a role indirectly. When your body metabolizes large amounts of carbohydrates, the composition of your sweat shifts in ways that may favor certain bacterial byproducts over others. If you’ve recently changed your diet and noticed the potato smell appearing around the same time, that connection is worth exploring. Try reducing sulfur-heavy foods for a week or two and see if the smell changes.
Hormones and Stress Sweat
Your body has two types of sweat glands. Eccrine glands cover most of your skin and produce the watery sweat that cools you down. Apocrine glands are concentrated in your armpits and groin, and they secrete a thicker fluid rich in proteins and lipids. This thicker sweat is what bacteria love most.
Apocrine glands are activated by stress, anxiety, and hormonal shifts rather than just heat. That’s why nervous sweat often smells worse than exercise sweat. Hormonal changes during puberty, pregnancy, menstruation, or menopause can alter the volume and composition of apocrine secretions, sometimes shifting your body odor into unfamiliar territory. If the potato smell appeared alongside a hormonal transition, that’s likely the mechanism at work.
When It Could Signal Something Else
Unusual body odor is occasionally linked to metabolic conditions where the body can’t properly break down certain compounds, allowing them to build up and escape through sweat. Phenylketonuria (PKU), for example, causes a musty or mousy body odor due to a buildup of phenylalanine byproducts. Trimethylaminuria produces a fishy smell. These conditions are rare and typically diagnosed in childhood, but milder variants can go unnoticed into adulthood.
Liver and kidney problems can also change how your sweat smells, though they tend to produce a bleach-like or ammonia-like odor rather than a potato smell. Uncontrolled diabetes sometimes causes a fruity or acetone-like scent. None of these conditions typically produce a starchy or earthy smell specifically, so a potato odor on its own is unlikely to indicate organ disease. That said, if the smell appeared suddenly, persists despite good hygiene, and comes with other symptoms like fatigue, digestive issues, or unexplained weight changes, it’s reasonable to bring it up with a doctor.
How to Reduce the Smell
Since bacteria are the primary driver, reducing bacterial activity on your skin is the most effective approach. Washing with an antibacterial soap, particularly in the armpits and groin, can significantly shift your skin’s microbial balance. Some people find that applying a thin layer of benzoyl peroxide wash (the same ingredient used for acne) to their underarms for 30 seconds before rinsing makes a noticeable difference within days. This works by lowering the overall bacterial population on the skin.
Antiperspirants reduce the amount of sweat that reaches the skin surface, giving bacteria less to feed on. For stronger results, apply antiperspirant at night when your sweat glands are less active, allowing the active ingredients to better penetrate the sweat ducts. Wearing breathable, moisture-wicking fabrics also helps by keeping your skin drier and less hospitable to bacterial growth.
Clothing itself can hold onto odor-causing bacteria. Synthetic fabrics like polyester tend to trap more odor than cotton or wool. If you’ve noticed the potato smell clinging to certain shirts even after washing, try soaking them in a vinegar solution before laundering, or switch to natural fibers for a while to see if that helps.
Dietary adjustments are the other lever you can pull. Cut back on sulfur-rich foods and increase your water intake, which dilutes the concentration of odor precursors in your sweat. Chlorophyll-rich foods like parsley, spinach, and wheatgrass have a mild internal deodorizing effect for some people, though the evidence is mostly anecdotal. Give any dietary change at least a couple of weeks before judging results, since it takes time for your sweat composition to shift.