What is the least washed part of the body? And Why it Matters

September 30, 2025 •

4 min read

According to a 2012 study, the average belly button is home to as many as 67 different species of bacteria. This startling fact highlights a common oversight in personal care routines, begging the question: What is the least washed part of the body? While many assume a quick shower gets the job done, several areas are consistently neglected, creating ideal environments for microbial growth and potential health issues.

Quick Summary

The belly button, behind the ears, and feet are commonly overlooked during washing, leading to the accumulation of bacteria, sweat, and dead skin. Poor hygiene in these hidden spots can result in unpleasant odors, irritation, and infections. Regular, targeted cleaning of these areas is essential for preventing such issues and maintaining overall health.

Key Points

The Belly Button is a Microbial Hotspot: Studies have shown the navel can harbor dozens of bacteria species, with 'innies' being especially prone to collecting debris, sweat, and dead skin that can lead to odor and infection.
Behind the Ears Collects Sebum and Sweat: This area has sebaceous glands that produce oil, which, combined with sweat and hair product residue, can result in bacterial growth, odor, and skin irritation if not cleaned properly.
Feet and Toes are Prone to Fungal Infections: The warm, moist environment between the toes is a perfect breeding ground for fungi, making active washing and thorough drying crucial for preventing conditions like athlete's foot.
Hard-to-Reach Areas Need Dedicated Attention: Body parts like the back and under fingernails are often forgotten but can accumulate significant dirt and bacteria. Using tools like a back brush or nail brush can help.
Proper Drying is Just as Important as Washing: For areas like the belly button and between the toes, ensuring the skin is completely dry after washing is essential to prevent excess moisture that fosters bacterial and fungal growth.
Neglecting Hygiene in These Spots Has Real Health Consequences: Ignoring these body parts can lead to skin irritation, foul odors, and various infections, highlighting the importance of a comprehensive hygiene routine.

The 'Grandmother Hypothesis' and Hidden Hotspots

For many, daily showering or bathing is a routine, but a comprehensive wash is often replaced with a quick rinse. The 'Grandmother Hypothesis,' a term coined by researchers at George Washington University, suggests that people neglect three key areas: behind the ears, between the toes, and the belly button. A study based on this hypothesis confirmed that these areas harbor distinct microbial communities due to infrequent cleaning. The reasons for neglecting these body parts are simple: they are often hard to see, feel, or reach.

The Belly Button: A Microbial Ecosystem

The navel, or belly button, is a prime example of an overlooked area. Its unique shape, especially with an 'innie,' creates a warm, moist, and dark crevice that is the perfect breeding ground for bacteria. In fact, the lint, dead skin, and sweat that collect in this area can harden over time into an 'omphalolith,' or navel stone. Regular, gentle cleaning is essential to prevent odor, irritation, and yeast infections.

Behind the Ears: Secretions and Buildup

Another commonly missed area is the skin behind the ears. This zone is rich in sebaceous glands, which produce sebum (an oily secretion), and sweat glands. The combination of oil, sweat, and residue from hair products can create a sticky, musty-smelling buildup. If neglected, this can lead to bacterial overgrowth and skin conditions like eczema. A simple swipe with a soapy washcloth is often enough to keep this area clean and fresh.

Feet and Toes: The Perfect Habitat for Fungus

Your feet carry you all day but are often only rinsed by soapy water running down the body. The moist, dark, and warm environment between the toes is an ideal habitat for fungi and bacteria to thrive, which can cause athlete's foot and other infections. Proper foot hygiene involves actively washing and, most importantly, thoroughly drying the feet, especially between the toes. According to the CDC, regular foot inspection is also key for overall foot health.

More Overlooked Areas and How to Address Them

Beyond the 'big three,' several other body parts often go unwashed or are washed improperly:

The Back: Due to its hard-to-reach nature, the back is frequently neglected, making it susceptible to acne and other skin issues. A long-handled brush or loofah can be helpful.
Under Fingernails: Dirt and bacteria can accumulate under the nails, which can easily be spread. A dedicated nail brush is an effective tool.
Inner Thighs: This area can trap sweat and bacteria, leading to chafing and discomfort. A good lather and rinse during a shower will help.
Elbows: Thick skin on the elbows can become rough and discolored with neglected exfoliation. A gentle exfoliant or washcloth scrub can help remove dead skin cells.

A Simple Guide to Comprehensive Cleaning

Here’s how you can incorporate these neglected spots into your regular hygiene routine:

Belly Button: For innies, use a cotton swab moistened with mild, antibacterial soap and water once or twice a week. For outies, a washcloth and soap suffice. Always dry thoroughly afterward.
Behind the Ears: Use a soapy washcloth or your fingers to gently scrub the area behind and around the ears daily. Don't forget the earlobes and the crease where they meet the head.
Between the Toes: Lather with soap and actively scrub between each toe during your shower. The most critical step is drying thoroughly to prevent fungal growth, which can be done with a towel or even a hairdryer on a low, cool setting.
The Back: Use a back brush with a long handle or a washcloth to reach and scrub your entire back. This helps prevent acne and removes accumulated sweat and oil.
Under Fingernails: Use a nail brush and soap to scrub under your fingernails to remove trapped dirt and germs, especially after manual work.

Comparison of Commonly Neglected Body Parts


Body Part	Common Issues from Neglect	Why it's Neglected	Recommended Cleaning Method	Frequency of Cleaning
Belly Button	Odor, infection, omphaloliths, yeast infections	Hidden, moist crevice; often just rinsed by water	Cotton swab with mild soap for innies; washcloth for outies	1-2 times per week
Behind the Ears	Odor, eczema, bacterial infections, irritated skin	Out of sight, out of mind; location of sebaceous glands	Soapy washcloth or fingers, gentle rubbing	Daily
Between the Toes	Athlete's foot, fungal infections, bacteria buildup	Hidden, moist area; prone to bacteria and fungi growth	Actively scrub with soap and dry thoroughly	Daily
The Back	Acne, skin irritation, oil and sweat buildup	Hard to reach; requires a tool for proper scrubbing	Long-handled back brush or loofah	Daily or as needed
Under Fingernails	Trapped dirt, debris, and germs; spreads bacteria	Microscopic spaces trap grime; easy to overlook	Use a nail brush with soap and water	Daily

Conclusion: Beyond the Standard Wash

While there is no single definitive answer to what is the least washed part of the body, the belly button, behind the ears, and feet consistently rank high on the list. Ignoring these areas is not merely an aesthetic issue but a health hazard that can lead to unpleasant odors, irritation, and infection. Incorporating a few extra seconds of mindful cleaning into your routine can make a significant difference. By paying attention to these hidden hotspots, you can proactively maintain better personal hygiene and avoid preventable health problems. Making a conscious effort to scrub these often-forgotten zones ensures your entire body, from head to toe, gets the comprehensive clean it deserves.

For more information on proper foot hygiene and preventing infections, visit the Centers for Disease Control and Prevention: Healthy Habits: Foot Hygiene.

Frequently Asked Questions

For most people, cleaning the belly button once or twice a week is sufficient. If you have an 'innie,' use a cotton swab with mild, antibacterial soap and water. For an 'outie,' a soapy washcloth will suffice. Always ensure the area is dried completely afterward.

A 'cheesy' or unpleasant smell behind the ears is often caused by the buildup of sebum (skin oil), sweat, and bacteria. This area contains sebaceous glands, and if not washed regularly, these secretions can accumulate and produce odor.

During your shower, use soap and your fingers or a washcloth to actively scrub between each toe. The most critical step is to dry the area thoroughly afterward, as excess moisture encourages fungal infections like athlete's foot.

Yes. Neglecting to clean your navel can trap dirt, dead skin, and bacteria, leading to irritation, foul odor, and even infections, including yeast infections.

To reach your entire back, use a long-handled back brush or a loofah with soap. This helps remove oil and sweat, preventing back acne and other skin issues in this hard-to-reach area.

Yes, neglecting to clean areas like the feet, belly button, and behind the ears can lead to a range of issues, including fungal infections (like athlete's foot), bacterial overgrowth, unpleasant odors, and skin irritation or eczema.

The 'Grandmother Hypothesis' is a term used by researchers for the theory that people tend to neglect washing specific body parts—behind the ears, between the toes, and in the belly button—potentially leading to distinct microbial differences in these areas.