Smelly Feet and Sweaty Feet: 6 Causes and the Medicines That Actually Work

6 days ago

17 min read

Foot odour (bromhidrosis) is the smell produced when the bacteria that normally live on the skin break down sweat and shed skin cells into volatile fatty acids and sulphur compounds. Sweat itself has almost no smell, so the odour comes from bacteria, not from being unclean. In many people an unusually strong smell has a skin condition behind it, especially pitted keratolysis and excessive foot sweating (plantar hyperhidrosis), and both have clear treatments.

This article separates the 6 kinds of foot odour seen in the clinic, with generic drug names, strengths, how to use them and how long they should take to work, so readers can tell where their own problem lies and what kind of treatment fits.

What causes smelly feet? The 3-step process behind the odour

Foot odour does not come from a single step. All three of the following must happen together.

Sweat. The soles have the densest sweat glands in the body, about 600–700 glands per square centimetre. Both feet together hold roughly 250,000 sweat glands and can produce up to about 200 millilitres a day in hot weather.
Trapped moisture. Sweat that cannot evaporate because it is trapped in socks and closed shoes makes the outer skin layer soggy and soft, which becomes food and a home for bacteria.
Bacterial breakdown. Bacteria such as Corynebacterium, Kytococcus sedentarius, Micrococcus and Brevibacterium break down leucine in sweat into isovaleric acid (a sour smell like spoiled cheese) and break down sulphur-containing amino acids into thiols (a smell like rotten eggs or onion).

The practical point is that effective treatment must fix at least two of these three. Washing alone lowers the bacteria only briefly and does not reduce sweat, so the smell returns within a few hours.

What conditions can cause smelly feet? 6 types to tell apart

Pitted keratolysis. Small pits scattered over the soles, no itch or little itch, a very strong smell, and often excessive foot sweating as well.
Foot odour from bacteria breaking down sweat (bromhidrosis). The skin of the soles looks completely normal and does not itch. The smell is moderate to strong and goes away after washing the feet.
Excessive foot sweating (plantar hyperhidrosis). The soles are wet, pale and wrinkled, with no itch. The smell is a later consequence. The sweating is clearly heavy, enough to soak the socks.
Fungal infection of the feet (tinea pedis). Peeling and white, soggy skin between the toes, with obvious itch and a musty smell.
Erythrasma. A flat red-brown patch with fine scale between the toes, mildly itchy or not itchy, with a musty smell. It looks very much like a fungal infection.
Immersion foot and shoe allergy rash. Red, soggy skin that stings more than it itches, usually after feet stay wet for a long time or along the shoe straps.

The next five sections describe each type under the same set of subheadings so they can be compared directly.

Type 1 · Pitted keratolysis

Appearance. Shallow round pits about 1–7 millimetres across on the soles and heels, scattered in groups. Sometimes the pits merge into a crater with a scalloped edge. They are most visible when the feet are wet or after soaking. The surrounding skin may be pale and soft. The smell is so strong that people nearby notice it as soon as the shoes come off. Most cases do not itch, and some people feel a sharp pain when walking.

Cause. Gram-positive bacteria, especially Kytococcus sedentarius and Corynebacterium, release enzymes that digest keratin in the outer skin layer until pits form. It occurs in people whose feet stay damp all the time, such as soldiers, athletes, people who wear rubber boots or safety shoes, and people who already sweat a lot from the feet.

Severity and urgency. It is not a dangerous disease and does not spread into the bloodstream in healthy people, but it affects quality of life and confidence a great deal. It is also the condition most often misdiagnosed as a fungal infection, so antifungal creams do not work because they target the wrong organism.

When to see a doctor. See a doctor when the smell is strong enough to affect daily life, when 4 weeks of self-applied antifungal medicine has brought no improvement, or when you can clearly see pits on the soles. The correct treatment is a topical antibiotic combined with sweat reduction, not an antifungal.

Type 2 · Foot odour from bacteria breaking down sweat (bromhidrosis) with normal skin

Appearance. A clear smell, but the skin of the soles looks completely normal: no pits, no peeling, no redness, no itch. The smell is stronger in the evening after a full day in shoes and almost disappears after washing the feet. This is the most common type.

Cause. A normal or somewhat high amount of sweat, plus the skin's resident bacteria and poorly ventilated shoes. Factors that make it worse include wearing the same pair of shoes every day without time to dry, synthetic socks that do not absorb sweat, and not drying between the toes after a shower.

Severity and urgency. It is not dangerous, and most cases can be controlled by reducing sweat and bacteria without antibiotics.

When to see a doctor. See a doctor when you have kept the feet clean and changed shoes properly for at least 4 weeks but the smell still disrupts your life, or when the skin starts to change, for example pits, peeling or redness. That means it is no longer simple bromhidrosis.

Type 3 · Excessive foot sweating (plantar hyperhidrosis)

Appearance. The soles are so wet that footprints show on the floor, socks are soaked and need changing during the day, and shoes wear out unusually fast. The skin of the soles is pale, wrinkled and soft, like skin soaked in water for a long time. Many people also sweat heavily on the palms or underarms. The smell is a consequence, not the original problem.

Cause. Primary focal hyperhidrosis comes from an overactive sympathetic nervous system, which controls the sweat glands. It usually starts before age 25, affects both sides equally, can run in the family in up to about one third of cases, and usually does not cause sweating during sleep. Secondary hyperhidrosis, which affects the whole body, happens at night, or starts after age 25, needs a search for other causes such as an overactive thyroid, diabetes, menopause, a chronic infection or a medicine side effect.

Severity and urgency. It is not life-threatening, but it is the starting point of pitted keratolysis, fungal infection of the feet and slipping falls, and it is the condition in this group with the clearest stepwise treatment.

When to see a doctor. See a doctor when foot sweat is so heavy that socks must be changed during the day, when ordinary antiperspirants are not enough, or when heavy sweating has only just started in an adult, affects the whole body, happens during sleep, or comes with weight loss, palpitations or fever, which need an internal cause ruled out first. Read more at What causes excessive sweating?

Type 4 · Fungal infection of the feet (tinea pedis) with odour and itch

Appearance. It starts between the toes, especially between the little toe and the fourth toe, with white, soggy, crumbly skin and cracks, and clear itching, especially when the shoes come off. Some people have fine powdery scale over the whole sole and along the edge of the foot in a moccasin pattern. The toenails may be thick, cloudy and yellow as well.

Cause. Dermatophyte fungi, mostly Trichophyton rubrum and Trichophyton interdigitale, picked up from shared wet floors such as communal showers, swimming pools and temples, and from shoes that never dry completely. It is found in about 15–25% of adults.

Severity and urgency. It is not serious in most people, but the cracks between the toes let bacteria into the deeper skin and can cause cellulitis. This risk is much higher in people with diabetes, swollen legs, varicose veins or weak immunity.

When to see a doctor. See a doctor when 4 full weeks of antifungal cream has not helped, when it spreads to the top of the foot or into the nails, or when the foot becomes swollen, red and hot, which is a sign of a secondary bacterial infection. To learn how to tell different kinds of peeling skin apart, read What causes peeling feet?

Type 5 · Erythrasma between the toes, the fungus look-alike

Appearance. A flat red-brown or light brown patch with a fairly clear edge and fine powdery scale, usually between the toes, and sometimes also in the groin or under the breasts. It itches slightly or not at all and has a musty smell. Its key feature is that it looks so much like a fungal infection that the naked eye cannot tell them apart.

Cause. The bacterium Corynebacterium minutissimum, not a fungus, so it does not respond to most antifungal medicines. It is more common in people with obesity, people with diabetes and people who sweat heavily.

Severity and urgency. It is not dangerous, but it is the classic reason for “I have used antifungal cream for months and it will not go away”, because the wrong type of organism is being treated.

When to see a doctor. See a doctor when a rash between the toes does not respond to antifungal medicine. Under a special light (Wood's lamp) in the clinic, erythrasma glows coral red, which separates it from a fungal infection immediately without waiting for a culture result.

Type 6 · Prolonged wet feet, immersion foot and shoe allergy rash

Appearance. Red, soggy, pale skin that stings more than it itches after the feet have been wet for many hours or days. If it is a contact allergy to shoes, the rash is red and itchy along the shoe straps or across the whole top of the foot, equal on both sides, and the skin between the toes is usually normal, which is the clue that separates it from a fungal infection.

Cause. Long contact with water and irritants damages the skin barrier, or an allergy to substances in shoes, such as potassium dichromate in tanned leather, accelerators in rubber and resin glues.

Severity and urgency. Most cases clear when the feet are kept dry and triggers are avoided, but broken, soggy skin makes a secondary infection easy.

When to see a doctor. See a doctor when the rash has not improved 1–2 weeks after the feet are kept dry, or when pus, pain, swelling or redness begins. Read more at What causes immersion foot?

Telling smelly feet apart yourself with 4 questions

Look at the soles while the feet are wet. Do you see small pits? Yes = think of pitted keratolysis first.
Does it itch or not? Itch between the toes with white, soggy skin = fungus or erythrasma. No itch at all but a strong smell = pitted keratolysis or bromhidrosis.
Do the socks get so wet that you must change them during the day? Yes = excessive foot sweating is the underlying cause and must be treated at the same time.
How many weeks have you used antifungal medicine? 4 weeks with no improvement = it is very likely not a fungus. Stop guessing and have a doctor scrape and test the skin.

A skin scraping tested with KOH solution in the clinic takes about 10–15 minutes to give a result, and it is far more reliable than judging by eye.

What medicine can be applied for smelly feet? Antibacterial medicines in real use

For pitted keratolysis and bromhidrosis that do not respond to general care, the main medicine is a topical antibiotic, always used together with sweat reduction.

Clindamycin 1% solution, gel or lotion. Apply a thin layer over the soles and between the toes 1–2 times a day for 2–4 weeks. It is the one dermatologists choose most often.
Erythromycin 2% solution or gel. Apply twice a day for 2–4 weeks. It can be used instead when clindamycin causes irritation.
Mupirocin 2% ointment. Apply 2–3 times a day for 1–2 weeks. It suits people with only a small patch or with cracks as well.
Benzoyl peroxide 5% wash or gel. Use it to wash the feet once a day as an add-on to reduce the number of bacteria. A caution is that it bleaches socks and towels.
For erythrasma, topical clindamycin or erythromycin are used as well. For widespread or resistant cases, the doctor may consider a short course of oral erythromycin, depending on body weight and underlying conditions.

What shows it is working. The smell usually drops clearly within the first 1–2 weeks, while the pits on the soles take about 3–4 weeks to become shallower and smooth. What shows it is not working is the same smell after 4 weeks, which usually means the sweating has not been dealt with, or the wrong group of disease was diagnosed from the start. Choosing the medicine, strength and duration that suit each person is the doctor's decision after examining the feet.

Medicine to reduce foot sweat: how to use aluminium chloride 20% so that it works and does not sting

Aluminium chloride hexahydrate 15–20% in an alcohol base is the first-line medicine for excessive foot sweating, and it is the one people most often use incorrectly, so they conclude it does not work.

The correct way to use it

Apply at bedtime only, because the sweat glands are least active at night and the medicine can actually plug the sweat gland ducts.
The skin must be completely dry before applying. If the feet are still damp, the medicine reacts with water to form hydrochloric acid and stings badly.
Wash it off in the morning.
At first apply 3–4 nights a week until sweating decreases, then cut down to 1–2 nights a week to maintain the result.
Most people start to see results within 1–2 weeks.

Common side effects are stinging and irritation, which can be reduced by applying to completely dry skin, applying less often, or applying a moisturiser in the morning after washing it off. Do not apply to broken skin, open wounds or skin that has just been shaved.

When creams are not enough: next options for heavy foot sweating

Treatment of excessive sweating follows clear steps, and you move up a step only when the previous one is truly not enough.

Iontophoresis (a weak electric current passed through water). Soak the feet in a tray of water carrying a weak electric current for 20–30 minutes at a time, 3–4 times a week at first, then cut down to 1–2 times a week to maintain the result. It suits people who cannot tolerate topical medicine. It must not be used in people who are pregnant, have a pacemaker or have metal implanted in the body.
Botulinum toxin type A injection blocks the nerve signals that tell the sweat glands to work. The effect lasts about 4–6 months and the injection must then be repeated. It hurts more on the soles than at other sites, so numbing is needed first. A possible side effect is temporary weakness of the small muscles of the foot.
Oral anticholinergic medicines such as glycopyrrolate or oxybutynin are used when sweating is heavy at several sites. Start at a low dose and adjust upward. Common side effects are dry mouth, blurred vision, constipation and difficulty passing urine, so they must be used under a doctor's care and are not suitable for people with glaucoma or prostate problems.

Results of each method differ from person to person, and the choice of method must always be assessed and carried out by a doctor.

Antifungal medicine when odour comes with itch and peeling skin

If testing shows that the problem really is a fungal infection of the feet, the medicines used are

Terbinafine 1% cream once a day for 1–2 weeks for the type between the toes.
Clotrimazole 1% cream or ketoconazole 2% cream twice a day for 2–4 weeks.
The rule people miss most often is to keep applying for another 1–2 weeks after the skin looks normal, because stopping the moment it looks cured often leads to a relapse.
For the moccasin type over the whole sole, or when the nails are involved, creams are often not enough. The doctor may consider oral medicine such as terbinafine or itraconazole, which requires assessing liver function and other medicines being taken first.

What to avoid completely is over-the-counter creams that mix a steroid with an antimicrobial, because they make the rash look better for a while, then the infection spreads wider and becomes much harder to diagnose.

6 things that make feet smell even worse

Soaking the feet in very hot water for a long time makes the outer skin layer soggy and damages its barrier.
Scrubbing the soles hard every day scrapes the skin and opens the way for bacteria.
Keeping on with antifungal cream without ever testing is the number one reason pitted keratolysis and erythrasma never go away.
Wearing the same pair of shoes every day. Shoes wet with sweat need at least 24 hours to dry properly.
Spraying deodorant over the top without reducing sweat masks the smell for only a few hours and does not fix the cause.
Sprinkling thick powder into socks that are already wet. The powder clumps with sweat into damp lumps that stick to the skin and add to the mustiness.

Foot and shoe care that really changes the result

Dry between the toes completely after every shower, especially between the little toe and the fourth toe. This one step gives the most benefit for the effort put in.
Change socks every day, and during the day if you sweat a lot. Choose cotton or sweat-wicking fibres and avoid pure nylon.
Rotate at least 2 pairs of shoes so each pair rests and dries for at least 24 hours. Take the insoles out to air as well.
Choose breathable shoes. Real leather with ventilation holes or canvas is better than sealed rubber or imitation leather. Safety shoes and rubber boots are clear risk factors.
Keep toenails short and cut straight to reduce places where moisture collects and to reduce ingrown nails.
Do not walk barefoot on shared wet areas such as communal showers and pool edges, to lower the chance of picking up fungus.

Can smelly feet be fixed permanently? Realistic expectations

The answer depends on the type. Pitted keratolysis and erythrasma can be cured with a full course of topical antibiotic together with sweat reduction, but they can come back if the feet return to the same damp conditions. Fungal infection of the feet can be cured but has a high relapse rate if shoes and socks are not managed. Primary excessive foot sweating is a chronic condition that can be controlled but not permanently cured. Treatment is therefore about keeping the symptoms at a level that allows normal life, and it must be kept up continuously.

Beware of advertising that guarantees a permanent cure in one session, because that goes against the nature of this condition.

Smelly feet in children and teenagers

School-age children and teenagers often have foot odour, because they wear closed school shoes all day, usually just one pair, and are at an age when the sweat glands become more active with hormones. The most effective approach in this group is to manage shoes and socks first, not to start with medicine.

A caution: high-strength antiperspirants and oral anticholinergic medicines should not be used on a child without advice and must be assessed by a doctor first. If a child has foot odour together with skin peeling in sheets or blisters, they should be examined for other skin diseases.

Smelly feet in people with diabetes: why more care is needed than in other people

In people with diabetes, a change in foot odour is not only about confidence, because damaged nerve endings mean they do not feel pain when there is a wound, and reduced blood supply to the feet makes wounds heal slowly and become infected easily.

Signs that need a doctor soon include a smell that changes to a rotten or unusually sweet smell, fluid or pus, skin turning dark or black, deep cracks between the toes, and a swollen, red, hot foot even without pain. People with diabetes should check the soles and between the toes every day, and should not cut hard skin or use peeling medicine on their own.

What does the doctor check when you come about smelly feet?

Look at the skin of the soles and between the toes, especially for shallow pits when the feet are wet, which are often missed at home.
Scrape the skin and test with KOH solution to confirm or rule out fungus. The result is known in 10–15 minutes.
Examine under a Wood's lamp to look for the coral-red glow of erythrasma.
Assess the level of sweating and its effect on daily life to choose the treatment steps.
Look for an internal cause when secondary excessive sweating is suspected, for example by checking thyroid function and blood sugar.
Patch testing for contact allergy when an allergy to something in the shoes is suspected.

In short

Foot odour comes from bacteria breaking down sweat, not from being unclean. Washing alone is therefore not enough if sweat is not reduced.
Small pits on the soles when the feet are wet = pitted keratolysis. It is treated with a topical antibiotic, not an antifungal.
Itch between the toes with white, soggy skin = fungus or erythrasma. The two use different groups of medicine, so it must be tested first to be sure.
Socks so wet they must be changed during the day = excessive foot sweating is the underlying cause. It must always be treated at the same time.
Aluminium chloride 20% must be applied at bedtime on completely dry skin and washed off in the morning. Applying it wrongly is the main reason for stinging and for thinking it does not work.
If you can only do one thing, use antifungal medicine on your own for no more than 4 weeks, and if there is no improvement, stop guessing and go to a doctor for a scraping test.

Frequently asked questions

Why do my feet suddenly smell?

A smell that has only just started usually comes from one of three things. The first is more sweat from hot weather, more activity on the feet, or new shoes that are more closed than before. The second is a new organism, such as a fungus picked up from shared wet floors, or bacteria that have multiplied until pitted keratolysis develops. The third is a change in the body, such as puberty, weight gain, pregnancy, an overactive thyroid, diabetes, or certain medicines that cause more sweating. If the smell has just begun together with changes in the skin of the soles, such as pits, peeling or redness, it means there is a real skin disease and not only a hygiene issue, and it should be examined.

What disease causes smelly feet?

An unusually strong foot odour usually fits one of three main conditions. The first is pitted keratolysis, caused by bacteria digesting keratin until the soles have pits 1–7 millimetres across and a very strong smell. The second is bromhidrosis, from bacteria breaking down sweat while the skin is still normal. The third is excessive foot sweating (plantar hyperhidrosis), which is the starting point of the other two. In addition there are fungal infection of the feet and erythrasma, which cause a musty smell together with a rash and itch. Telling which one it is matters a great deal, because the medicines are entirely different groups.

What medicine can be applied for smelly feet?

It depends on the cause. For pitted keratolysis or erythrasma, the main medicine is a topical antibiotic: clindamycin 1% or erythromycin 2% applied 1–2 times a day for 2–4 weeks. Some people also use mupirocin 2% or benzoyl peroxide 5% as an add-on. If there is heavy foot sweating as well, aluminium chloride hexahydrate 20% must be applied at bedtime on completely dry skin alongside. Antifungal medicine such as terbinafine 1% or clotrimazole 1% is used only when there is truly a fungal infection. A caution: if 4 weeks of self-applied antifungal medicine has not helped, it usually means it is not a fungus. Choosing the medicine and strength that suit each person is the doctor's decision after examination.

Can smelly feet be fixed permanently?

It depends on the cause. Pitted keratolysis, erythrasma and fungal infection of the feet can really be cured when the right group of medicine is used for the full course, but they can come back if the feet return to the same damp conditions. Primary excessive foot sweating is a chronic condition that can be controlled well but is not permanently curable. Care that keeps the result lasting means managing the starting point continuously: dry between the toes, change socks every day, rotate shoes so they dry for at least 24 hours, and use an antiperspirant to maintain the effect 1–2 nights a week. Be wary of advertising that guarantees a cure in one session.

What kind of shoes stop feet from smelling?

The principle is to choose shoes that let moisture out and have time to dry. Real leather with ventilation holes and canvas are better than rubber, imitation leather and sealed plastic, which hold moisture all day. Removable insoles that can be aired help a lot because that is where sweat collects most. More important than brand or material is having at least 2 pairs of shoes to rotate, so each pair dries for at least 24 hours, and wearing cotton or sweat-wicking socks changed every day. For safety shoes and rubber boots that a job requires, take them off to rest and air them whenever there is a chance, and use an antiperspirant as well.

Does excessive foot sweating need treatment?

It should be treated when it affects daily life, for example socks so wet they must be changed during the day, feet that slip inside shoes, or odour and skin disease following, because heavy sweat is the starting point of both pitted keratolysis and fungal infection of the feet. Treatment begins with aluminium chloride hexahydrate 20% at bedtime. If that is not enough, the next steps are iontophoresis, botulinum toxin type A injection, whose effect lasts about 4–6 months, or oral anticholinergic medicine for people who sweat at several sites. What must always be separated out first: if sweating has only just started in an adult, affects the whole body or happens during sleep, an internal cause such as an overactive thyroid or diabetes must be looked for first.