What Causes Body Odor? Strong, Sour or Musty Smell, and What Helps
Image: Armin Kübelbeck · CC BY-SA 3.0 · resized
Written by นพ. ภัทร วรวุทธินนท์, dermatologist
Body odor comes from sweat that is nearly odorless on its own, mixed with fluid from apocrine sweat glands and bacteria that normally live on the skin. It does not always mean you are dirty or not taking care of yourself. Most people can improve a strong smell with thorough washing, drying the skin well, and using an antiperspirant or deodorant. If the odor stays strong despite regular care, or the smell changes suddenly, see a dermatologist to look for a cause.
This article explains what causes body odor, whether a sour, musty or fishy smell can point to illness, how to care for it at home, and when to see a doctor.
What causes body odor: two kinds of sweat glands and skin bacteria
The skin has two main kinds of sweat glands, and they work differently.
Eccrine glands: Found over most of the body, especially the palms, soles and face. Their main job is to help cool you. This sweat is nearly odorless.
Apocrine glands: Found in the armpits, groin and around the nipples. They become clearly active from puberty. Their secretion is thicker, and it is also nearly odorless when it first leaves the gland.
Most body odor starts when bacteria that normally live on the skin break down apocrine secretions, skin oils and skin cells into smelly compounds such as short-chain fatty acids. Bacteria often involved include Corynebacterium species, Staphylococcus hominis, Staphylococcus epidermidis and Cutibacterium. These are ordinary skin microbes, not a sign that you are unclean.
It is therefore common for body odor to become noticeable after puberty, when apocrine glands fully start working. Underarm odor is frequent in this period, and it is usually strongest where apocrine glands, hair and moisture meet, such as the armpits and groin.
Image: Le-prof-histo · CC BY-SA 4.0
If you sweat much more than usual, the skin stays damp longer, bacteria work more easily, and the smell can get stronger. Read more about excessive sweating (hyperhidrosis) (in Thai) and how to tell ordinary heat-related sweating from a hidden medical cause (in Thai).
Why you can still have odor after a shower
A common question is why a strong body smell can remain after a shower, even if you bathe every day. The usual reasons are not simply that you did not wash enough.
Bacteria live in skin folds, at the base of hairs and in pores. Washing the surface can reduce odor for a while, but apocrine glands can keep releasing fluid after you shower.
Folds such as the armpits, under the breasts, the groin or between the toes, if not dried well, become damp again quickly. The smell can return within a few hours, especially in hot, humid weather.
Clothes or towels that have held sweat can keep the odor. Your skin may be clean, but putting on the same shirt brings the smell back.
Using only a deodorant that covers the smell, without reducing sweat, leaves the skin damp.
Sometimes another factor is involved, such as a skin infection, heavy sweating, or odor from food or medicine.
This kind of lingering odor is a description, not a disease name. If you wash, dry well and use an antiperspirant correctly and the smell is still clear, a dermatologist can help look for a cause. You do not need to blame yourself for being unclean.
Can body odor be a sign of illness?
Body odor can sometimes relate to an illness, but the type of smell alone cannot diagnose a disease. For most people, a sour or pungent smell still comes from sweat and skin bacteria. The table below is a rough guide to what a smell may be linked with, and what to do.
Type of smell | Likely cause | What to do |
Sour | Short-chain fatty acids that bacteria make from sweat, often a fermented-food kind of sourness, common in the armpits and usually not a sign of disease | Wash thoroughly, dry well, use an antiperspirant; see a dermatologist if it stays strong |
Pungent or “green” / musty | Often still from skin bacteria. Many people use this wording for a sharper smell than a sour one. The smell alone does not point to a disease | Care for it as you would everyday odor. If the smell changes clearly or other symptoms appear, see a doctor |
Fishy | A rare condition called trimethylaminuria (fish odor syndrome), in which the body breaks down trimethylamine poorly. A fishy smell may be noticed in sweat, urine and breath. It can also be temporary after foods such as fish, eggs or beans, or related to liver or kidney disease | Do not conclude on your own that you have this condition. If a fishy smell is clear, persistent, or present in sweat, urine and breath, see a doctor to look for a cause |
Fruity or acetone (like nail-polish remover) | May relate to ketones in the body, such as poorly controlled diabetes, or when the body is using a lot of fat for energy | If you also have intense thirst, frequent urination, marked fatigue, fast breathing or confusion, go to a hospital promptly, because this can be an urgent problem |
Ammonia or urine-like | May relate to kidney problems, when waste is filtered less well and some of it may leave the body in the breath and sweat | If you also have swelling, unusual tiredness, a change in urine, or this smell is new without a clear reason, see a doctor. Do not diagnose from the smell alone |
Other smells | A musty, sulfur-like smell on the breath may relate to liver disease. A strong foot smell may be smelly feet and sweaty feet (in Thai). Painful lumps, pus or tunnels in the armpit or groin may be hidradenitis suppurativa (HS) (in Thai). In young children, a smell from one nostril may mean a foreign object is stuck there | Look at other symptoms too. If the smell changes suddenly, there are signs of a systemic illness, or there is a rash, lump or pain, see a doctor |
A change in smell without a clear reason from food, medicine or daily care is something you can ask a doctor about. It is not something to feel ashamed of. A fishy smell now and then after seafood is not the same as a rare metabolic condition.
What makes body odor stronger
Factors that often make body odor stronger include:
Heavy sweating, from heat, exercise, stress, or excessive sweating (in Thai)
Underarm hair, which gives sweat and bacteria a surface to cling to, so the smell lasts longer
Synthetic fabrics, especially polyester, which hold moisture and odor more than cotton or other natural fibers
Food, such as garlic, onion, strong spices, alcohol, or other strong-smelling foods, which can temporarily change the smell of sweat and breath
Medicines, including some antidepressants, which may increase sweating or change odor
Hormones: puberty, menstrual cycles, pregnancy and menopause can change sweating and smell
Stress and anxiety, which can stimulate apocrine glands
Higher body weight, which can make skin folds stay damp
Skin infections, such as fungi or bacteria in folds
Medical conditions, such as diabetes, liver disease or kidney disease, as noted in the table above
If sweat causes an itchy or burning rash or hives, it may not be only an odor issue. Read more about sweat-related rashes (in Thai). Dark underarms can have several causes; see dark underarms (in Thai).
What you can do yourself: deodorant, antiperspirant, and odor that stays in clothes
Most people can start managing body odor at home as follows.
Wash and dry thoroughly
Wash the armpits, groin, skin folds and feet with soap, then dry well, especially in the folds.
You do not need to scrub hard or wash so often that the skin becomes dry and irritated. Irritated skin can stay damp and smell more easily.
An antibacterial soap may help reduce bacteria for some people, but if the skin becomes dry or itchy, go back to a gentle cleanser.
How a deodorant differs from an antiperspirant
Deodorant: Helps cover odor or reduce the bacteria that cause it, but does not reduce the amount of sweat.
Antiperspirant: Usually contains an aluminum salt such as aluminum chloride. It temporarily plugs sweat ducts, so you sweat less, the skin is drier, and bacteria make less odor. Many products combine both in one bottle.
How dermatologists often suggest applying antiperspirant
Apply it to clean, completely dry skin at night. You sweat less at night, so the active ingredient can work better and is less likely to irritate.
Let it dry before you go to bed or put on a shirt.
Do not apply it right after shaving, because freshly shaved skin is easily irritated.
If the skin becomes red or itchy, leave more time between applications, try a different formula, or ask a doctor. Do not buy a steroid cream to apply on your own.
A higher-strength antiperspirant may need to be chosen by a doctor.
Clothes and odor that will not wash out
Choose cotton or other breathable natural fabrics. Avoid tight synthetic shirts. After exercise, change out of a sweat-damp shirt promptly.
Wash sweaty clothes instead of leaving them in a damp pile. Fabric that stays damp holds odor in the fibers, especially synthetic sportswear.
If odor stays in a shirt after washing, try washing sooner, using enough detergent, rinsing well, and drying thoroughly. Warmer water may help if the fabric allows it. Sometimes odor is so set in synthetic fibers that it is hard to clean; you may need to change how you wash or stop using that shirt.
Damp shoes and socks easily become smelly. Rotate them and let them dry. Read more about smelly feet and sweaty feet (in Thai).
If nothing you try helps, how dermatologists approach treatment
If regular self-care still leaves a strong body odor, a dermatologist will first look for the cause: whether it is mainly glands and bacteria, heavy sweating, a skin infection, or another condition. A general dermatology approach may include:
Topical aluminum chloride, at a strength suited to the person, applied to dry skin at night to reduce sweat
Topical antibacterials or antibiotic creams, when bacteria or a skin infection play a part
Botulinum toxin injections to reduce sweating, when heavy sweating is driving the odor. The effect is temporary and is considered person by person
Laser hair removal, which may reduce the surface that sweat and bacteria cling to, in some people
Treating related causes, such as excessive sweating, a skin infection, or a systemic condition linked to the odor
The right care differs from person to person, and results vary. This article describes a general approach. It does not say which procedures or devices any clinic offers. For advice that fits you, a doctor should examine you and plan care individually.
When to see a doctor
See a dermatologist if:
You have cared for the problem properly for a while, and a strong body odor still interferes with daily life or confidence
The smell changes suddenly, without a clear reason from food, medicine or exercise
You suddenly sweat much more than usual, or you have night sweats without a clear reason
You have a rash, pain, itching, lumps or pus in the armpit, groin or skin folds
You have a fishy, acetone or ammonia smell that is not from food, together with other symptoms
Go to a hospital promptly if a fruity or acetone smell comes with intense thirst, frequent urination, marked fatigue, fast breathing or confusion, because this may be diabetic ketoacidosis, which needs urgent care.
Frequently asked questions about body odor
Can body odor be stopped so that it does not come back?
Most people can control body odor better with thorough washing, drying the skin and using an antiperspirant regularly. Sweat glands and skin bacteria are a normal part of the body, so the smell can return if care lapses or if triggers such as heat, stress or hormones appear. Some causes, such as a skin infection or excessive sweating, often improve when the underlying problem is treated. Results vary from person to person. No method can promise that the odor will never return.
Does shaving underarm hair help reduce odor?
Shaving or trimming underarm hair helps reduce odor for many people, because hair gives sweat and bacteria a surface to cling to. Shaving alone is usually not enough. You still need to wash, dry well and use an antiperspirant or deodorant. Do not apply a strong antiperspirant right after shaving, because freshly shaved skin is easily irritated. Laser hair removal is another option that may reduce hair over a longer period for some people. Ask a doctor first if your skin is easily irritated or you have a rash in the armpit.
Is body odor different in men and women?
Both men and women can have body odor. It is not only a matter of cleanliness. Underarm odor is discussed more often in men, who on average may sweat more and have more underarm hair, but the strength of the smell varies widely from person to person. In women, hormones around the menstrual cycle, pregnancy or menopause can change sweating and smell. The main care is the same: wash thoroughly, dry well and use an antiperspirant correctly.
What causes a fishy body odor?
A fishy smell in sweat, urine or breath can come from a rare condition called trimethylaminuria, in which the body breaks down trimethylamine poorly because the enzyme from the FMO3 gene does not work fully. The smell may be stronger after eating fish, eggs, liver or beans, and when you are stressed or sweating a lot. A fishy smell can also be temporary after food, or in some people related to liver or kidney disease. Do not conclude on your own that you have this condition. If a fishy smell is clear and persistent, see a doctor to look for a cause.
Is body odor abnormal in children?
Before puberty, apocrine glands are not fully active, so young children usually do not have adult-type body odor. If a child has an unusual strong smell, especially from one nostril, the breath or urine, or a new smell without a food-related reason, a doctor should assess them. Sometimes a foreign object is stuck in the nose, or an uncommon metabolic condition is involved. Around puberty, underarm odor is common and is often managed with hygiene and an antiperspirant. Children should not be blamed for being dirty.
How should I use a deodorant and an antiperspirant?
A deodorant helps cover odor or reduce bacteria, but does not reduce sweat. An antiperspirant temporarily plugs sweat ducts, so the skin is drier and there is less odor. Many products combine both in one bottle. A usual method is to apply antiperspirant to completely dry skin at night, let it dry, then in the morning you can shower and add a deodorant if you wish. If the skin becomes red or itchy, leave more time between applications or change the formula, and ask a doctor if it does not settle.
See a dermatologist at คลินิกเฉพาะทางผิวหนัง Siam Dermatology
If you are worried about body odor, a strong smell, or a change in how you smell, you can see a dermatologist at คลินิกเฉพาะทางผิวหนัง Siam Dermatology. The doctor will take your history, examine your skin and suggest care that fits you. More details: general dermatology care (in Thai)
Book via LINE @siamderm or call 061-448-7000 (+66 61 448 7000)
Hours: Monday–Friday 16:00–20:00 and Saturday–Sunday 08:00–16:00
Wednesday: no general dermatology consultations (laser and procedures only)
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