WHY DOES ONE ARMPIT SMELL WORSE THAN THE OTHER?

Noticed one armpit smells more than the other? It’s not your imagination. Maybe your left side always seems a little funkier after the gym, or your right side refuses to stay fresh no matter how much deodorant you apply. It's a common issue that many people experience, and it can be linked to a number of reasons including body chemistry, sweat glands, and daily habits.

But here’s the good news: with a few tweaks (and the right deodorant), you can get both sides smelling equally fresh again.

THE SCIENCE BEHIND WHY ONE ARMPIT SMELLS MORE

Before you start questioning your hygiene routine, know this: our bodies are not perfectly symmetrical. One side is often more dominant (and more active) than the other.

Sweat gland asymmetry

You have two types of sweat glands—eccrine (the watery kind) and apocrine (the odor-causing kind). Sometimes, one armpit simply has more active apocrine glands, which leads to stronger odor.

Dominant side differences

If you’re right-handed, you naturally move and sweat more on that side. More movement = more sweat = more bacteria which are responsible for odor to develop.

Microbiome variations

The mix of bacteria under each arm isn’t identical. Certain bacteria, like Corynebacterium, are more likely to produce noticeable odor, and if one armpit hosts more of that type of bacteria, you’ll smell it.¹

So, the “one smelly armpit” phenomenon isn’t weird—it’s just your biology doing its thing.

Man touring with a backpack with both straps on each arm

COMMON CAUSES YOU MIGHT OVERLOOK

Beyond natural asymmetry, there are other factors that can cause one armpit to smell more than the other. These include:

Bacterial imbalance: Overwashing or harsh soaps can disrupt your underarm microbiome, which allow odor-causing bacteria to thrive unevenly.
Trapped sweat: Tight clothing or fabrics that don’t breathe can trap moisture, and give one armpit a perfect environment for bacteria to multiply.
Product buildup: Deodorant or antiperspirant residue can build up over time, especially if you don’t exfoliate. That buildup can trap sweat and bacteria close to the skin, making one side smell stronger.
Shaving habits: If you shave one armpit more often (or use an old razor), tiny nicks can cause irritation and create a space where bacteria love to hang out.

FACTORS THAT MAKE IT WORSE

Sometimes, external or internal factors can make the imbalance even more noticeable.

Hormonal changes: Fluctuations in hormones (like during stress, menstruation or menopause) can change your sweat composition.
Stress: Emotional sweat from your apocrine glands are richer in proteins. Basically a buffet for odor-causing bacteria.
Thyroid conditions: An overactive thyroid can cause excessive sweating (called hyperhidrosis), sometimes unevenly distributed.
Clothing choices: Tight sleeves or synthetic fabrics can lock in sweat, especially on your more active side.
Antiperspirant application: Applying unevenly or missing spots can make one armpit less protected from sweat and odor.

HOW TO FIX UNEVEN ARMPIT ODOR

The fix starts with balance. Restoring your skin’s microbiome, improving hygiene habits, and using the right deodorant.

Switch to an antibacterial antiperspirant

Choose a deodorant designed to target odor-causing bacteria while keeping you dry. Products like Degree Advanced Dry Protection use MotionSense® technology to release bursts of freshness every time you move.

Exfoliate regularly

Use a gentle scrub or exfoliating cloth once or twice a week to remove buildup and dead skin cells.

Reset your underarm balance

After washing with a good body wash use a gentle, skin-friendly cleanser or toner—such as diluted apple cider vinegar—to help refresh and care for the delicate underarm area.

Reapply strategically

If one side sweats more, it’s okay to apply an extra swipe of antiperspirant there. Just make sure your skin is dry first for maximum protection.

WHEN TO SEEK EXPERT ADVICE

If the odor sticks around even after washing, reach out to a healthcare professional. Ongoing odor can signal an underlying issue like an infection or thyroid imbalance. A doctor can pinpoint the cause and guide you toward the right treatment.

FAQs

Why does my right armpit smell even after a shower?

When one armpit smells stronger than the other, it often comes down to differences in sweat gland activity, bacteria, or how you wash and apply deodorant. Your dominant arm tends to sweat more because it moves more, creating a warmer environment where odor-causing bacteria thrive. To help, make sure you’re washing thoroughly (especially after workouts), drying completely, and applying deodorant or antiperspirant evenly on both sides.

How can I reset my armpit pH?

Your skin naturally maintains a slightly acidic pH, which helps control bacteria and odor. To support this balance, stick with gentle cleansers and avoid harsh scrubs or alkaline soaps that can disrupt your skin barrier. Some people use a diluted apple cider vinegar rinse or pH-friendly body wash to help refresh the area, but consistency and mildness are key—never apply undiluted vinegar, and always moisturize afterward to avoid irritation.

What does thyroid sweat smell like?

There’s no single “thyroid smell,” but changes in hormone levels—including those linked to thyroid conditions—can sometimes affect how your sweat smells or how much you perspire. For example, an overactive thyroid (hyperthyroidism) may cause you to sweat more, which can intensify normal body odor. If you notice a sudden or persistent change in your sweat’s smell along with other symptoms (like weight changes, anxiety, or fatigue), it’s best to check in with a healthcare provider.

If one armpit keeps out-smelling the other, it’s your body’s way of saying something’s off-balance, but it’s totally fixable. With the right products, habits, and a little science on your side, you can keep both underarms fresh and in sync.