Persistent body odor despite regular showering, deodorant use, and clean clothes usually points to something happening beneath the surface: your biology, diet, clothing materials, hormones, or occasionally an underlying health condition. Basic hygiene handles the most common causes of odor, so when it doesn’t work, the source is typically something soap can’t reach.
How Body Odor Actually Works
Fresh sweat is nearly odorless. The smell happens when bacteria on your skin break down compounds in your sweat, and not all sweat is created equal. Your body has two types of sweat glands, and they produce very different fluids.
Eccrine glands cover most of your body and produce the watery sweat you notice during exercise or heat. It’s mostly water with traces of minerals, lactate, and urea. Apocrine glands are concentrated in your armpits, groin, and around your nipples. They secrete an oily substance loaded with proteins, lipids, and steroids. When bacteria feast on these oily compounds, they produce the sulfur-containing and acidic byproducts you recognize as B.O. That’s why your armpits smell worse than your forearms, even when both are sweaty.
Showering removes bacteria and sweat temporarily, but apocrine glands keep secreting throughout the day. If your skin’s bacterial population regrows quickly, or if your apocrine glands are particularly active, odor returns within hours regardless of how thoroughly you cleaned up that morning.
Your Clothes May Be Working Against You
One of the most overlooked causes of persistent odor is fabric choice. Research from the University of Alberta found that polyester absorbs significantly more odor-causing compounds from sweat than plant-based fabrics like cotton or viscose. The reason comes down to chemistry: polyester repels water but attracts the oily, smelly compounds in sweat. Cotton does the opposite, absorbing the water and leaving more of the odorants behind.
What makes polyester especially problematic is that it holds onto those compounds long after other fabrics have released them. Nylon and wool also absorb a lot of odorants initially, but they dissipate them within about 24 hours. Polyester keeps them trapped. If your workout shirts or undershirts are synthetic, switching to cotton or viscose blends can make a noticeable difference. And if your polyester clothes already have a permanent musty smell even after washing, the embedded odorants may be nearly impossible to fully remove.
Foods That Come Out Through Your Skin
Certain foods produce sulfur compounds that survive digestion, enter your bloodstream, and get excreted through your sweat glands and breath. Garlic and onions are the most well-known culprits. The sulfur compounds they contain can linger in your system for hours, producing an odor that no amount of showering will eliminate because it’s being pushed out from the inside.
Cruciferous vegetables like broccoli, cabbage, Brussels sprouts, and cauliflower release sulfuric acid during digestion, which intensifies body odor, breath, and gas. These are healthy foods worth eating, but if you’re troubleshooting a persistent smell, tracking whether it worsens after meals heavy in these ingredients can help you identify a pattern.
Hormones and Stress Sweat
Hormonal shifts directly change how your sweat glands behave. During puberty, rising levels of DHEA (a precursor hormone that converts into testosterone and estrogen) activate both the apocrine sweat glands and the sebaceous glands in your skin. Sebaceous glands produce sebum, an oily substance that protects skin but also contributes to body odor. This is why body odor often appears or intensifies during adolescence, even in kids who bathe regularly.
Stress triggers a different kind of sweat entirely. When you’re anxious or under pressure, your body releases adrenaline, which activates apocrine glands rather than eccrine ones. That means stress sweat contains the protein-rich, oily mixture that bacteria love, not the mostly-water eccrine sweat you produce during a hot day. If you’ve noticed you smell worse after a stressful meeting than after a jog, this is why.
Menopause and perimenopause can also shift body odor. Hormonal fluctuations trigger hot flashes and increased sweating, and declining estrogen levels can change the composition of sweat and skin oils.
Medications That Increase Odor
Several common medications increase sweating or alter body odor as a side effect. Antidepressants including fluoxetine (Prozac), paroxetine (Paxil), and venlafaxine (Effexor) are known to increase sweat production. So are pain medications like tramadol and codeine, nerve pain drugs like pregabalin and gabapentin, and even the common acid reflux medication omeprazole.
Some drugs also change mouth odor. Opioids and certain antidepressants reduce saliva production, which allows odor-causing bacteria to thrive in the mouth. Antibiotics and antifungals can alter the balance of bacteria on your skin and in your gut, sometimes producing new or stronger odors. If your body odor changed around the time you started a new medication, that connection is worth exploring with your prescriber.
Metabolic and Organ-Related Causes
When your body can’t get energy from glucose, whether due to uncontrolled diabetes, a very low-carb diet, or prolonged fasting, it burns fat instead. That process produces ketones, which build up in your blood and get expelled through your breath and skin. The result is a distinctive fruity or acetone-like smell, similar to nail polish remover. On a ketogenic diet, this is expected and temporary for most people. In someone with unmanaged diabetes, it can signal a dangerous condition called diabetic ketoacidosis that needs immediate medical attention.
Liver and kidney problems produce their own characteristic odors. When the liver is failing, it can’t properly filter certain sulfur compounds from the blood. The result is a condition called fetor hepaticus: a musty, sweet, sometimes fecal smell on the breath, often compared to rotten eggs, garlic, or scorched fruit. The dominant compounds are dimethyl sulfide (which smells garlicky and pungent) and methyl mercaptan (which smells like rotten cabbage). Kidney failure produces a different smell. When your kidneys stop filtering urea effectively, it builds up in your blood and gets expelled through your breath, creating an ammonia or bleach-like odor.
A rarer genetic condition called trimethylaminuria causes a strong, fishy body odor. People with this condition have a faulty version of a liver enzyme that normally converts a compound called trimethylamine into an odorless form. Without that conversion, trimethylamine builds up and gets released through sweat, urine, and breath. It’s diagnosed through a urine test that measures the ratio of trimethylamine to its odorless form. Genetic testing can confirm mutations in the responsible gene.
Bromhidrosis: When Odor Is the Condition
Bromhidrosis is the clinical term for chronic, abnormally strong body odor. It occurs when either apocrine or eccrine glands produce excessive secretions that become especially malodorous when bacteria break them down. It’s considered rare, but it’s a recognized medical condition with treatment options ranging from prescription-strength antiperspirants to procedures that reduce sweat gland activity. If your odor is persistent, strong, and unresponsive to standard hygiene measures, this diagnosis is worth discussing with a dermatologist.
When the Smell Isn’t Real
There’s one more possibility worth knowing about, especially if other people have told you they don’t notice an odor. Olfactory reference disorder is a condition where someone becomes preoccupied with the belief that they emit a foul smell, even though others can’t detect it or consider it only slight. People with this condition typically spend hours each day worrying about the perceived odor. They may shower excessively, change clothes multiple times, constantly check themselves by sniffing, and seek repeated reassurance from others.
Most people with olfactory reference disorder have poor insight into the condition, meaning they genuinely believe the smell is real, often because they can actually perceive it themselves. They commonly interpret other people’s unrelated actions (sitting far away, opening a window, touching their nose) as reactions to the odor. The condition can become severely isolating: many people avoid social situations, work, and public spaces out of embarrassment. It’s classified alongside obsessive-compulsive related disorders in the DSM-5 and responds to treatment. If multiple trusted people have told you they can’t smell anything unusual, and you still feel certain the odor is there, this is worth bringing up with a mental health professional.
Practical Steps Worth Trying
If you’ve ruled out medical conditions and medications, a few targeted changes often make a meaningful difference. Switch workout clothes and undershirts from polyester to cotton or cotton blends. Apply antiperspirant at night rather than in the morning, since sweat glands are less active during sleep, which allows the active ingredients to penetrate more effectively. Pay attention to whether your odor worsens after garlic-heavy or cruciferous-vegetable-heavy meals, and adjust timing if you’re heading into a social situation.
Consider whether you’re washing your armpits with an antibacterial or benzoyl peroxide wash, which reduces the bacterial population more effectively than regular soap. Some people also find that shaving or trimming armpit hair helps, since hair provides a larger surface area for bacteria to colonize and traps moisture against the skin. If none of these changes help, a dermatologist can evaluate you for bromhidrosis or other glandular issues, and basic blood work can screen for the metabolic and organ-related causes that produce odor from the inside out.