Why Does Body Odor Change?

The Hidden Science of Sweat, Skin & Everyday Life

Have you ever noticed that your body smells different after a stressful day, during a hormonal shift, or even after wearing a certain shirt?

It can feel mysterious and sometimes embarrassing, but body odor is not simply a sign of being “unclean.” It results from a fascinating interaction between sweat, skin microorganisms, hormones, daily habits and the environment around us.[1,2]

In other words, your body’s scent is not fixed. It can change as your body and surroundings change.

The First Surprise: Sweat Is Not Usually the Smelly Part

Fresh sweat is largely odorless. The familiar smell we call body odor develops mainly when naturally occurring microorganisms on the skin transform components of sweat and other skin secretions into smaller, volatile molecules that our noses can detect.[1,3]

Think of sweat and skin secretions as the raw ingredients and the skin microbiome as a tiny laboratory that transforms them.

Our skin hosts a diverse community of microorganisms, collectively known as the skin microbiome. This microbial community varies from person to person and from one area of the body to another.

The underarms provide a warm, moist environment where microorganisms can thrive. Research has particularly associated Corynebacterium species with characteristic axillary, or underarm, odor.[3,4]

However, odor is not created by one “bad” bacterium. It depends on the microorganisms present, the secretions available to them and the local skin environment.[3,5]

Two Types of Sweat, Two Different Jobs

Two types of sweat glands are especially important when understanding body odor.

Eccrine Glands

Eccrine glands are distributed across most of the body and release watery sweat directly onto the skin. Their primary role is helping regulate body temperature, particularly during exercise or hot weather.[1,2]

Apocrine Glands

Apocrine glands are concentrated in areas such as the underarms and groin and release their secretions into hair follicles. They become active around puberty.[1,2]

These secretions contain compounds that skin microorganisms can transform into noticeable odor molecules.[3,4]

This is one reason sweating during an intense workout may not smell exactly the same as sweating during a stressful situation.

Why Can Body Odor Change?

1.⁠ ⁠Stress Changes the Situation

Stress and anxiety can increase sweating, and the underarm area can respond strongly to emotional stimulation.[2,5]

The combination of moisture, glandular secretions and microbial activity can therefore make stress-related body odor seem different or more noticeable.

That is why five minutes before an important presentation can sometimes leave a more noticeable scent than thirty minutes outside on a warm day.

2.⁠ ⁠Hormones Can Influence Body Odor

Hormonal changes throughout life can affect sweating and body odor. Puberty is particularly important because apocrine glands become active around this stage. Hormonal changes associated with menstruation, pregnancy and menopause may also influence how a person perceives or experiences their usual body scent.[2,5]

There is no single “hormonal smell” that applies to everyone. Body odor remains highly individual.

So, if your usual underarm routine seems to work differently during a particular stage of life, the change may have a biological explanation.

3.⁠ ⁠Your Skin Microbiome Can Change

The microbial community of the underarm differs between individuals and can also be influenced by environmental and personal factors.[3,5]

Because microorganisms differ in how they transform skin secretions, changes in the microbial community can influence the intensity and character of body odor.

This helps explain why the same deodorant may perform differently from one person to another. Underarm care involves individual skin chemistry and microbiology, so it is not necessarily one-size-fits-all.

4.⁠ ⁠Food Can Leave a Temporary Signature

Certain foods and beverages can influence body odor. Garlic, onions, some strong spices and alcohol are among commonly reported examples.[2]

Foods may contribute in different ways. Some contain compounds that can ultimately be released by the body, while others may increase perspiration and indirectly make odor more noticeable.[2]

Rather than automatically eliminating foods, pay attention to patterns. If a particular food consistently seems to affect your body odor, that observation may be useful.

5.⁠ ⁠Your Clothes May Be Part of the Story

Sometimes the odor is not coming only from your skin. Your clothing can contribute too.

Textile fibres differ in how they interact with moisture, microorganisms and odor compounds. Research comparing cotton and polyester clothing after exercise found differences in microbial growth and odor development, with polyester shirts developing more intense and less pleasant odor in that study.[6]

This may explain a familiar experience: an athletic shirt smells clean after washing but develops an old odor surprisingly quickly once it becomes warm and damp again.

If body odor seems noticeably worse with particular clothes, consider the fabric and laundry routine as well as your skin.

6.⁠ ⁠Medications and Health Changes Can Affect Sweating

Some medications can increase sweating, a phenomenon known as drug-induced hyperhidrosis.[7] Changes in body odor or sweating can also occur alongside certain medical conditions.[2]

Most everyday fluctuations in body odor are not necessarily a cause for concern. However, a sudden or persistent unexplained change, particularly when accompanied by unusually heavy sweating or other symptoms, is worth discussing with a qualified healthcare professional.[2]

Deodorant can help manage everyday odor, but it should not be used to simply cover a significant unexplained change in your body.

Deodorant and Antiperspirant Are Not the Same Thing

Although the terms are sometimes used interchangeably, deodorants and antiperspirants serve different purposes.

Antiperspirants are designed to reduce perspiration. Many conventional antiperspirants use aluminum salts to reduce the amount of sweat reaching the skin.[1]

Deodorants are intended to help manage or mask odor without necessarily preventing normal perspiration.[1]

Depending on their formulation, deodorants may use fragrance or other ingredients intended to help manage the conditions associated with unwanted odor.

Sweating itself is a normal biological process and plays an important role in regulating body temperature. Managing body odor does not require treating normal perspiration as something shameful.

A Gentler, Smarter Underarm Routine

A few simple habits can help manage everyday body odor:

1.⁠ ⁠Wash gently and dry thoroughly. Keeping the underarm area clean and dry can help reduce the conditions that encourage unwanted odor.
2.⁠ ⁠Apply deodorant to clean, dry skin. Follow the directions provided for your particular product.
3.⁠ ⁠Be cautious after shaving. Freshly shaved skin can be more sensitive, particularly to fragranced products or essential oils.
4.⁠ ⁠Notice patterns. Stress, certain foods, medications, hormonal stages and clothing may help explain changes in your usual body odor.
5.⁠ ⁠Pay attention to clothing. Regular washing is important, and certain fabrics may retain or develop odor differently.[6]
6.⁠ ⁠Patch-test new personal-care products. “Natural” does not automatically mean irritation-free. Skin responses vary from person to person.

At Natura Touch, we see personal care as a partnership with the body rather than a battle against it.

A thoughtfully formulated deodorant can support everyday freshness without pretending that normal perspiration is something the body should never experience.

Body odor is not a personal failure. It is the result of chemistry, microbiology and everyday life meeting on the surface of your skin.

The Takeaway

Body scent can change because sweat, skin microorganisms, hormones, stress, diet, clothing, medications, health and the surrounding environment can all interact.[2,5]

Understanding the science behind those changes can replace embarrassment with something much more useful: awareness.

Listen to your body, care for your skin gently and choose personal-care products that suit your individual needs rather than expecting one routine to work identically for everyone.

Your body is not being difficult. It is communicating.

References

[1] DermNet. Antiperspirant. Updated August 2022. DermNet New Zealand.

[2] Cleveland Clinic. Body Odor: Causes, Changes, Underlying Diseases & Treatment. Medically reviewed March 4, 2022.

[3] Callewaert C, Hutapea P, Van de Wiele T, Boon N. Deodorants and antiperspirants affect the axillary bacterial community. Archives of Dermatological Research. 2014;306:701–710.

[4] James AG, Austin CJ, Cox DS, Taylor D, Calvert R. Microbiological and biochemical origins of human axillary odour. FEMS Microbiology Ecology. 2013;83(3):527–540.

[5] Di Cicco F, Evans RL, James AG, Weddell I, Chopra A, Smeets MAM. Intrinsic and extrinsic factors affecting axillary odor variation: A comprehensive review. Physiology & Behavior. 2023;270:114307.

[6] Callewaert C, De Maeseneire E, Kerckhof FM, Verliefde A, Van de Wiele T, Boon N. Microbial Odor Profile of Polyester and Cotton Clothes after a Fitness Session. Applied and Environmental Microbiology. 2014;80(21):6611–6619.

[7] DermNet. Drug-induced hyperhidrosis. DermNet New Zealand.

This article is intended for general educational purposes only and is not a substitute for professional medical advice, diagnosis or treatment.