Body Odor Explained: Why It Happens and How to Control It

Struggling with body odor (B.O)? You’re not alone. Sweat itself is odorless, but when it meets bacteria, things get funky. From diet to hygiene habits, many factors influence your scent. The good news? With the right approach, you can stay fresh all day. Let’s dive into the science—and solutions—of B.O..

What Is Body Odor?

B.O. is the unpleasant or distinctive smell produced when sweat interacts with bacteria on the skin. It typically arises from areas with a high concentration of sweat glands, such as the armpits and feet which is why we associate B.O. with sweat. 

B.O is influenced by factors like hygiene, diet, hormones, medical conditions and genetics. 

While B.O. is normal, extreme B.O. can be classified as a medical condition, known as bromhidrosis, osmidrosis or ozochrotia.

The Science Behind Body Odor

While sweat is actually odorless, B.O. occurs when sweat reacts with bacteria on your skin.

Let’s unpack the science behind sweat and ultimately B.O..

Your body has two types of sweat glands: eccrine and apocrine.

Eccrine glands are found all over the body and help regulate temperature by releasing sweat, mostly composed of water, with small amounts of salt and ammonia. This type of sweat is typically odorless.

Apocrine glands, on the other hand, are concentrated in areas like the armpits, breasts, genitals, eyelids, and ears. These glands become active during puberty and produce a milky fluid rich in proteins and lipids. When bacteria break down this fluid, they release the distinct smell known as B.O..

But why do humans produce B.O.? Research suggests an evolutionary link. Since apocrine glands activate during puberty and are clustered near the sex organs, some scientists believe B.O. plays a role in mating. Others theorize that it helps humans recognize blood relatives, including parents and siblings, through scent.

You’re most likely to experience B.O. in these areas:

• Armpits

• Feet

• Groin

• Genitals

• Belly button

• Behind the ears

• Pubic hair and other hair

Body Odor Through Different Life Stages

B.O. evolves throughout life due to hormonal changes, gland activity and lifestyle factors. Here’s how it shifts across different life stages:

Infancy and Childhood

Babies and young children typically don’t have B.O. because their apocrine glands remain inactive. Sweat is primarily produced by eccrine glands, which regulate body temperature but don’t cause odor.

Puberty

B.O. is triggered during puberty by hormonal changes. Between the ages of 8-13 in girls and 9-15 in boys, glands in the groin and armpit areas start secreting a protein- and lipid-rich fluid that bacteria break down, leading to the onset of B.O..

This is why preteens and teenagers often notice a sudden need for deodorant.

Adulthood

B.O. stabilizes during adulthood but can vary based on diet, hygiene, stress levels and overall health. Hormonal fluctuations—such as those from pregnancy or menstruation—can temporarily alter B.O., making it stronger or different.

As people age, apocrine gland activity declines, often leading to a less intense B.O..

Menopause

Along with hot flashes and night sweats, body odor is another bothersome symptom of menopause.

Many women notice a change in their body odor during menopause. A dip in estrogen can trigger night sweats and hot flashes, causing increased sweat and body odor.

Many women also experience anxiety or stress during menopause, which can also lead to unwanted odor.

What Causes Body Odor?

Unfortunately, many factors play a role in B.O. production. Common causes of B.O. include medical conditions, high stress levels, personal hygiene habits, diet and lifestyle.

Let’s dive deeper into each of these B.O. causes.

Medical Conditions

B.O. can be influenced by various medical conditions and medications. Understanding these factors is essential for effective management.

• Hyperthyroidism: Sweat and B.O. can be a result of an overactive thyroid. When you have an overactive thyroid, your body produces an abundance of sweat, even if you aren’t physically exerting yourself. Your doctor can test your blood or urine to see if you have hyperthyroidism.

• Diabetes: Diabetes patients may experience a sudden change in smell or B.O., due to high levels of blood glucose. The liver produces chemicals (ketones) that make their way through blood, urine or breath and can alter B.O..

• Obesity: Those who are overweight or obese tend to sweat more. Fat insulates the body and raises its core temperature, causing increased sweat production and B.O.. Obesity can also decrease airflow in sweaty areas, giving odor-causing bacteria the perfect climate to breed.

• Genetic Disorders: While rare, gene mutations can also affect B.O.. Trimethylaminuria is a condition where your body can’t break down the chemical compound, trimethylamine. As a result, the compound builds up in your body and is released through sweat, urine and breath.

• Hyperhidrosis: Hyperhidrosis is characterized by excessive sweating, which can lead to increased body odor. This condition may be primary (without an underlying cause) or secondary (resulting from another medical issue). Treatment options include prescription-strength antiperspirants, botulinum toxin injections, and, in severe cases, surgical interventions.

• Liver and Kidney Diseases: Liver and kidney diseases can result in the accumulation of waste products in the body, leading to distinctive B.O.. For example, kidney failure may cause a urine-like or ammonia-like smell, while liver disease can produce a musty odor. 

In addition to medical conditions, some medications can also alter your B.O.. For example:

• Antidepressants: Some antidepressants, such as fluoxetine, paroxetine, and venlafaxine, can increase sweating, leading to changes in B.O.. 

• Antihypertensives: Medications like clonidine, used to treat high blood pressure, may cause excessive sweating, contributing to B.O..

• Antipsychotics: Certain antipsychotic drugs can lead to increased sweating, which may result in changes in B.O.. 

• Anticholinergics: Medications with anticholinergic properties can reduce sweating, potentially leading to dry skin and an increased risk of bacterial growth, which may alter B.O.. 

• Antibiotics: Some antibiotics can disrupt the normal balance of bacteria on the skin, leading to changes in B.O..

High Stress Levels

Have you noticed that stress sweat smells worse than your typical post-workout stench? That’s because stress sweat originates from the apocrine glands, which produce proteins that bacteria love.

A 2022 study examined how emotional changes, including stress, affect skin odor and its impact on others. The researchers found that stress-induced sweat has a distinctive odor, which can be perceived by others and may influence social interactions. Another research indicates that stress sweat has a unique scent. The participants identified the odor of stress sweat as "similar to stir-fried leeks," suggesting that stress-induced sweat has a characteristic smell that differs from other types of sweat.

Personal Hygiene Habits

Practicing good personal hygiene habits can keep B.O. at bay.

Regular showers remove sweat, bacteria, and dead skin cells, preventing unpleasant smells. Using antibacterial soap and deodorants or antiperspirants helps fight odor-causing bacteria and control sweating. 

Additionally, wearing clean, breathable clothing reduces sweat buildup, while shaving or trimming body hair limits areas where bacteria can accumulate. Lastly, don’t forget oral hygiene—bad breath can contribute to overall B.O..

Read more: How to Stop Sweating So Much [14 Proven Solutions]

Diet

Certain foods, along with caffeine and alcohol consumption, can intensify unpleasant B.O..

Your liver metabolizes most of the alcohol you drink and excretes it through your urine. But if you drink too much or too fast, your liver has difficulty processing the alcohol. Instead, your body releases the excess alcohol through your breath and pores, resulting in stinky B.O..

Caffeine can also affect B.O.. Caffeine causes dry mouth, which can amplify bacteria and odor. Additionally, hot, caffeinated beverages can raise your body temperature and cause you to sweat more, leading to an increase in B.O..

Here are a few foods and diets that cause B.O.:

How to Keep Body Odor Under Control

In most cases, B.O. is treatable and manageable. Follow these expert tips to get rid of bad B.O.: 

1. Refine Your Personal Hygiene Routine 

Small changes to your hygiene can reduce B.O.:

• Shower daily, especially after exercise.

• Use antibacterial soap on sweaty areas like your armpits and groin to kill odor-causing bacteria.

• Trim or shave your armpits—research shows less hair can reduce sweat and odor.

• Launder clothes regularly and wash workout gear after use.

• Replace towels, loofahs, and washcloths frequently to avoid bacteria buildup.

2. Use the Right Deodorant

3. Apply a Stronger Antiperspirant

4. Wear Anti-Odor Clothing

5. Modify Your Diet

6. Try Natural Home Remedy Hacks

Kitchen and bathroom items can help: