Why do my underarms smell when I just showered?

September 30, 2025 •

5 min read

Approximately 2-4 million sweat glands exist across the human body, but sweat itself is virtually odorless. The unpleasant scent that leads you to ask, "Why do my underarms smell when I just showered?", is actually caused by bacteria on your skin breaking down the sweat.

Quick Summary

Lingering armpit odor despite showering is often caused by bacteria on the skin interacting with specific types of sweat. Issues can stem from ineffective washing techniques, product buildup, clothing choices, diet, hormonal changes, and medical conditions.

Key Points

Odor is caused by bacteria, not sweat: The smell comes from bacteria breaking down proteins and fats in apocrine sweat, not the sweat itself.
Your washing routine may be ineffective: Simply rinsing isn't enough; you need to use an antibacterial soap and scrub thoroughly to remove odor-causing bacteria and product buildup.
Dry your underarms completely: Moisture provides an ideal breeding ground for bacteria. Ensure your armpits are fully dry after showering before applying products.
Diet and clothing play a major role: Strong-smelling foods and synthetic fabrics can intensify body odor. Opt for natural, breathable fabrics and manage your intake of pungent foods.
Timing and product choice matter: Applying antiperspirant to dry skin at night is often most effective. Consider clinical-strength options if needed, and distinguish between deodorants and antiperspirants.
Underlying health issues can be the cause: If odor persists despite improved hygiene, consult a doctor to rule out medical conditions like hyperhidrosis, diabetes, or skin infections.

The Science Behind Lingering Underarm Odor

To understand why underarm odor persists even after a thorough wash, it is crucial to know how sweat and bacteria interact. The human body has two main types of sweat glands: eccrine and apocrine.

Eccrine glands are found all over the body and produce a clear, watery sweat that helps cool you down when you overheat. This sweat is essentially odorless.
Apocrine glands are concentrated in areas with hair follicles, such as the armpits and groin, and become active during puberty. They secrete a thicker, milky fluid that is high in proteins and lipids. While this fluid is initially odorless, the naturally occurring bacteria on your skin, particularly Corynebacterium and certain Staphylococcus species, feed on these compounds. The byproducts of this bacterial breakdown are what create the pungent, unpleasant body odor.

The warm, moist environment of the underarm is an ideal breeding ground for these bacteria. Therefore, if your showering routine doesn't effectively remove these microbes, or if other factors encourage their growth, the odor can reappear almost immediately.

Common Reasons for Persistent Odor

Several factors can contribute to stubborn underarm smell, even with regular bathing. These reasons range from simple hygiene oversights to deeper physiological issues.

Ineffective Washing Techniques

Many people rush through their shower, but a quick rinse often isn't enough to dislodge the bacteria and product buildup in the armpit area. You need to be intentional about scrubbing the area. Similarly, using a mild, fragrant soap may mask the smell temporarily but won't effectively kill the odor-causing bacteria. Incomplete rinsing can also leave soap and deodorant residue that traps bacteria and creates a perfect storm for odor.

Lifestyle and Dietary Factors

What you consume can have a direct effect on your body odor. The old saying, "you are what you eat," holds true in this case. Foods and beverages that can lead to a more noticeable scent include:

Garlic, onions, and cruciferous vegetables like broccoli and cabbage, which contain sulfur compounds.
Spices, including curry and cumin.
Red meat, which can leave a residue that intensifies odor during digestion.
Alcohol and caffeinated drinks, which can increase overall sweat production.

Other lifestyle habits, like wearing certain clothing materials, can also contribute. Synthetic fabrics like polyester trap heat and moisture against the skin, creating an ideal environment for bacteria to flourish.

Product Application and Hair

How and when you apply products matters significantly. Applying antiperspirant to damp skin, rather than fully dry skin, can prevent it from properly absorbing and blocking sweat glands. For optimal effectiveness, dermatologists often recommend applying antiperspirant at night, when you sweat less, giving the active ingredients time to work. Additionally, underarm hair traps moisture and provides a larger surface area for bacteria, which is why trimming or shaving the area can help reduce odor.

Hormonal and Stress Factors

Hormonal fluctuations, such as those experienced during puberty, menstruation, pregnancy, or menopause, can alter sweat production and composition, leading to changes in body odor. Furthermore, stress-induced sweat comes primarily from the apocrine glands and is thicker and more pungent than sweat caused by heat. Managing stress through relaxation techniques can therefore have a beneficial effect on your underarm scent.

Medical Conditions

In some cases, persistent body odor can be a symptom of an underlying medical condition. These include:

Hyperhidrosis: A condition characterized by excessive sweating.
Diabetes: High blood sugar levels can sometimes produce a fruity body odor.
Liver or kidney disease: These can lead to a bleach-like or ammonia-like smell due to toxin buildup.
Skin infections: Fungal or bacterial infections, like trichomycosis axillaris, can cause a very foul odor.

A Guide to Effective Underarm Care

By tweaking your hygiene and lifestyle, you can combat persistent underarm odor. Here is a comparison of different products and a list of best practices to consider.


Feature	Deodorant	Antiperspirant
Primary Function	Masks and neutralizes odor with fragrance and antimicrobial agents.	Actively blocks sweat glands with aluminum salts, reducing perspiration.
Active Ingredients	Alcohol, antimicrobial agents, fragrance.	Aluminum-based compounds.
Best Used For	Managing odor if you don't sweat excessively.	Controlling both sweat and odor, especially if you sweat a lot.
Application Tip	Can be applied after showering.	Most effective when applied at night to dry skin.

Tips for Eliminating Stubborn Odor

Use an antibacterial cleanser: Switch to a body wash containing ingredients like benzoyl peroxide or tea tree oil to target odor-causing bacteria more effectively.
Dry off completely: Bacteria thrive in moisture. After showering, ensure your underarms are completely dry before applying any product. A hairdryer on a cool setting can help.
Consider hair removal: Less hair means less moisture trapped and less surface area for bacteria to grow. Trimming or shaving can increase the effectiveness of your products.
Change your clothes often: Wear clean clothes daily. For activewear, wash it immediately after use, as sweat quickly embeds odor into the fabric.
Choose breathable fabrics: Opt for natural materials like cotton, linen, or moisture-wicking fabrics that allow the skin to breathe and reduce trapped moisture.
Manage stress: Incorporating relaxation techniques like yoga or meditation can reduce stress-induced sweating from your apocrine glands.
Dietary adjustments: Experiment with reducing pungent foods like garlic, onions, and spices, as they can be excreted through your sweat.

For some, an underarm shower rinse specifically formulated to deep clean and remove product buildup can be an effective addition to their routine. This can help reset the underarm's microbial environment and boost the effectiveness of deodorants and antiperspirants.

Conclusion: When to Seek Professional Advice

While persistent underarm odor after showering can be frustrating, for many people, it's a manageable issue that can be resolved with simple changes to their hygiene routine and lifestyle. By understanding the role of bacteria and apocrine sweat, and by making strategic adjustments—such as using an antibacterial soap, ensuring thorough drying, and applying the right product at the right time—you can often achieve lasting freshness.

However, if the odor persists despite these measures, or if you experience a sudden and unexplained change in your body odor, it may be time to consult a healthcare provider or a dermatologist. They can help rule out underlying medical conditions, such as hyperhidrosis or other infections, and recommend clinical-strength treatments if necessary.

Understanding the microbial basis of body odor in pre-pubescent children and teenagers

Frequently Asked Questions

Using an antibacterial soap or a body wash containing ingredients like benzoyl peroxide or tea tree oil can help eliminate the odor-causing bacteria more effectively than regular soap. For sensitive skin, milder, pH-balanced options are recommended.

While hair itself doesn't smell, it can trap moisture and provide a larger surface area for bacteria to live, which can lead to a more noticeable odor. Trimming or shaving underarm hair can make it easier to clean the area and reduce the smell.

Deodorant masks and neutralizes odor, while antiperspirant actively blocks sweat glands to reduce perspiration. If you sweat heavily, an antiperspirant is more effective. Some products combine both functions.

Yes, foods with pungent aromas or high sulfur content, such as garlic, onions, red meat, and some spices, can be excreted through your sweat and affect your body's overall odor.

Stress activates apocrine sweat glands, which produce a thicker, protein-rich sweat that bacteria can feast on. This results in a more pungent and sour-smelling odor compared to regular sweat.

If you experience a sudden, noticeable change in your body odor or if the odor persists despite improving your hygiene and lifestyle, you should see a doctor. This could indicate an underlying medical condition like hyperhidrosis, diabetes, or a skin infection.

Applying antiperspirant at night is more effective because you sweat less while you sleep. This gives the product's active ingredients more time to properly absorb into your sweat ducts and block perspiration.