Super smelly feet? Some people host bacteria that produce volatile sulfur compounds

• Hyperhidrosis — a condition that causes overactive sweat glands — can make your feet extra stinky.
• You may also have particularly smelly feet if you get a fungal infection called Athlete's foot. 
• If you notice a bit of a rotten egg smell, you may have Kytococcus sedentarius bacteria on your feet.

It's normal for feet to have some smell, but having especially stinky feet can be unpleasant, embarrassing, and a sign that something may be wrong. 

There are many reasons why your feet might suddenly smell more funky or foul than usual — you might have a sweating disorder, bacterial overgrowth, or a skin infection.

Here are five reasons why your feet might suddenly smell so bad and how you can treat the problem.

1. Hyperhidrosis

Hyperhidrosis occurs when your sweat glands are overactive, making you sweat heavily even when you aren't overheated or exercising. This can happen to your whole body, or you might just sweat excessively in one area like your feet. 

There are many types of bacteria on the bottom of your feet, and "excess sweat creates moisture, which makes bacterial growth greater," says Dr. Stephen Mandy, a professor of dermatology at the University of Miami Health System.

These bacteria break down skin oils and dead skin cells, and this process can create a strong foot odor akin to vinegar, Mandy says.

How to treat it: You can prevent excessive sweating at home with antiperspirant foot creams. Your doctor can also provide prescription strength antiperspirant if the home remedies don't work.

2. Athlete's foot

Athlete's foot is a common fungal infection that can cause feet to smell sour or similar to a funky cheese.

"Fungi like to grow in warm, moist areas, so when your feet sweat inside your shoes and socks, it creates the perfect environment for fungus," says Dr. Dendy Engelman, a board certified cosmetic dermatologist at the Shafer Clinic.

Like bacteria, fungus can create a smelly odor — especially if the infection is concentrated between your toes.

Along with a bad smell, athlete's foot can also cause itching, cracking, or peeling skin of or around the affected area.  

How to treat it: You can usually treat athlete's foot at home using an over-the-counter antifungal medication like clotrimazole or miconazole. If the infection lasts longer than two weeks, or comes back multiple times, it's best to see a doctor for treatment.

3. Pitted keratolysis

If you're prone to heavy sweating, the soles of your feet may have an overgrowth of bacteria called Kytococcus sedentarius.

Not everyone is affected by these smelly bacteria, but about 10% to 15% of people have an overgrowth of Kytococcus sedentarius, which makes feet smell particularly bad.

Like other bacteria, Kytococcus sedentarius produce an odor when they break down oils and dead skin cells on your feet. But unlike other bacteria, they also produce volatile sulfur compounds, which create a rotten egg smell.

If the bacteria overgrow too much, it can cause a condition called pitted keratolysis, which may lead to an itchy infection on the soles of your feet.

How to treat it: If you have an overgrowth of bacteria or pitted keratolysis, your doctor can prescribe an antibiotic cream like clindamycin or erythromycin.

4. Stress

When you're under a lot of stress, your nervous system revs up, which causes you to stress sweat.

Stress sweat is different from the regular sweat you get from exercising or hyperhidrosis. Stress sweat is produced by apocrine glands in your skin and tends to have more fatty acids and proteins than regular sweat.

This type of sweat takes longer to evaporate, so it has a longer time to react with the bacteria on your skin and produce odor.

How to treat it: If you're struggling with stress sweat, you can manage it using techniques like exercising and journaling. This can help calm your nervous system and curb symptoms like sweating.

5. Bad hygiene

Your foot hygiene can have a big effect on how your feet smell. Here are a couple of key do's and don'ts for good foot hygiene:

How to prevent foot odor

Here are a few techniques you can use to treat bad foot odor:

• Walk barefoot at home: "It's important to allow your feet to breathe, so removing your shoes and socks whenever you can will help — at home is a good place to start," Engelman says.
• Wear open-toed shoes: Wearing sandals or other breathable shoes in the warmer months can help reduce wetness and bacterial growth.
• Wash your feet with antibacterial soap: When you wash your feet, it's best to use antibacterial soap to kill off any bacterial overgrowths.
• Use talcum powder: You can apply talcum powder to your feet, which helps soak up excess wetness and prevent "moist environments that odor-causing bacteria and fungi thrive in," Engelman says.
• Use foot antiperspirant: Over the counter foot antiperspirants work by blocking your sweat glands, which keeps your feet dryer during the day.
• Get foot Botox: "In extreme cases, Botulinum toxin can be used to treat the soles of the feet in order to prevent excessive sweating," Engelman says.

Insider's takeaway

"Your feet can smell for a variety of reasons, but most commonly, it's due to excessive sweating or wetness that causes a foul odor," Engelman says.

Having good foot hygiene and wearing the right socks and shoes can help cut down foot odor and leave your feet feeling better. 

If at-home methods aren't working, you should see a dermatologist to determine if you need prescription creams or medications.