Sweat is a natural bodily function that helps regulate body temperature and remove excess salts and toxins from the body. However, when sweat mixes with bacteria on your skin, it can start to smell unpleasant. Understanding what causes sweat to smell can help you take steps to control body odor.
What Is Sweat?
Sweat, also known as perspiration, is mainly water produced by sweat glands in the skin. Sweat contains minerals like sodium, potassium, calcium, and magnesium. It also contains lactate, urea, and traces of ammonia.
There are two types of sweat glands:
- Eccrine glands – Found all over the body, eccrine glands produce a watery sweat to cool the body when its temperature rises. This type of sweat is mostly odorless.
- Apocrine glands – Concentrated in the armpits and groin, apocrine glands are linked to hair follicles. The oily sweat they produce contains pheromones and proteins.
Apocrine sweat itself has no odor, but when it mixes with bacteria on your skin, it can cause body odor. The armpits and groin have high concentrations of apocrine glands and are prone to unpleasant smells if you don’t practice good hygiene.
What Causes Sweat to Smell?
Sweat only starts to smell when it comes into contact with bacteria on your skin. The bacteria feed on sweat, especially in warm and moist areas like the armpits and groin. As the bacteria multiply, they produce waste products that have a characteristic sweaty odor.
Some of the bacteria species that cause body odor include:
- Staphylococcus hominis
- Staphylococcus epidermidis
- Corynebacterium jeikeium
- Corynebacterium urealyticum
- Corynebacterium tuberculostearicum
- Corynebacterium xerosis
- Micrococcus luteus
- Propionibacterium avidum
- Propionibacterium acnes
These bacteria feed on the proteins and fatty acids in sweat. Their metabolic processes produce pungent fatty acids like isovaleric acid and propionic acid that cause underarm odor. Staphylococcus species also break down sweat into substances like thioalcohols that have a characteristic sweaty smell.
Factors That Can Make Sweat Smell Worse
While everyone perspires, some people seem to have much stronger body odor than others. Here are some factors that can cause increased body odor:
- Genetics – Your genes influence the chemical makeup of your sweat, which affects how odor-causing bacteria react with it.
- Diet – Eating spicy foods, garlic, onions, and red meat can make sweat more pungent.
- Stress – Stress causes you to sweat more, providing more food for bacteria.
- Obesity – Obese people tend to sweat more.
- Illnesses – Diseases like diabetes and kidney failure can also impact sweat composition and smell.
- Medications – Some medicines like birth control pills, antibiotics, and certain vitamins can increase odor.
- Puberty – Sweat tends to become more pungent after puberty due to hormone changes.
Maintaining good personal hygiene can help control sweat smell, even if you’re prone to body odor.
Where on the Body Does Sweat Smell the Most?
The areas where sweat smells the most are those with the highest concentration of apocrine sweat glands. These include:
- Armpits (axillae) – The armpits have a very high density of apocrine glands but a low surface area. This creates an ideal warm and moist environment for bacteria to thrive.
- Groin – The groin area houses many apocrine glands and is prone to odors.
- Pubic region – Similar to the groin, this area is warm and moist, allowing bacteria to flourish.
- Breasts – The skin under the breasts provides an ideal location for bacteria to grow.
- Feet – Sweaty feet offer a good growth medium for bacteria that cause foot odor.
- Belly button – The belly button can accumulate sweat, dead skin, and dirt that breeds bacteria.
- Facial hair – Food and sweat particles trapped in facial hair can produce odors.
- Scalp – Sweat and oils secreted by hair follicles can cause scalp odor, especially if you have lots of hair.
Paying attention to cleaning and hygiene in these areas can help reduce body odor.
How to Prevent Sweat from Smelling
You can take steps to prevent sweat from smelling by inhibiting bacterial growth. Here are some tips:
- Bathe regularly – Wash sweat and bacteria off your skin daily.
- Use antibacterial soap – Soaps containing antibacterial ingredients like triclosan can reduce bacteria.
- Deodorant/antiperspirant – Aluminum-based compounds in these products stop sweat and bacterial growth.
- Clean clothes – Change sweat-soaked clothes. Avoid re-wearing unwashed clothes.
- Shave – Shaving can help eliminate bacteria living in hair follicles.
- Apply powder – Powders with antibacterial ingredients absorb moisture and decrease odor.
- Wear breathable fabrics – Clothes that breathe minimize sweat buildup.
- Control sweat medically – Prescription antiperspirants or Botox injections reduce sweating.
Maintaining a hygienic lifestyle and using odor-fighting products can help keep sweat smells at bay.
Body Odor Treatment Options
If you already have body odor, there are ways to get rid of unpleasant smells:
- Wash with antibacterial soap – Scrubbing with medicated soap reduces bacteria.
- Apply topical wipes – Wipes with chlorhexidine or benzethonium chloride kill bacteria.
- Use oral antibiotics – Antibiotics like erythromycin taken for 1-2 weeks can eliminate odor-causing bacteria.
- Try iontophoresis – Running a weak electrical current through water can control excessive sweating.
- Get Botox – Botox injections block nerves that activate sweat glands.
- Consider MiraDry – This FDA-approved treatment uses microwave energy to destroy sweat glands.
- Try probiotics – Probiotic supplements promote “good” bacteria that outcompete odor-causing bacteria.
- Apply topical acid – Wiping the skin with glycolic or salicylic acid solutions can inhibit bacteria.
Discuss professional treatment methods for excessive sweating and smell with your healthcare provider.
When to See a Doctor
You should consider consulting a physician if:
- You have very strong body odor even with good hygiene.
- Odor is accompanied by increased sweating.
- Foul smells persist despite over-the-counter treatments.
- Odor affects your relationships and self-esteem.
A doctor can diagnose any underlying condition contributing to extreme body odor. They may prescribe stronger antiperspirants, antibiotics, or refer you to a dermatologist for specialized treatment options to control sweat and smell.
Conclusion
In summary, sweat smells when it mixes with bacteria on your skin that break it down into pungent fatty acids and other compounds. Areas with many sweat glands like the armpits and groin are most prone to odors. Practicing good hygiene, using antiperspirants and deodorants, wearing breathable fabrics, and controlling sweat medically can help prevent odors. If you already have body odor, antibacterial soaps, oral antibiotics, iontophoresis, Botox, and specialized treatments can help eliminate smells. See a doctor if odor is very strong or doesn’t respond to over-the-counter remedies.