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Washing your clothes | When and Why - Sweat, body odor, rashes & your clothes

Updated: Jan 15, 2023

Smelly clothes are a general signal of the buildup of bacteria, sweat, keratin, dirt, and debris on your clothes. Read more...



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Why do I need to think about washing my clothes?

Technically, your skin is one of your body’s first lines of defense against the environment. However, during the course of the day and night, there is a good chance that it is getting a little help from your clothes.

Many people segment their wardrobes into daily wear, workwear, leisurewear, workout gear, formal wear, party wear, and perhaps even your Sunday best. Some items get a lot of use while lounging around, other items while working out and sweating quite a bit, and some are just exposed to the environment a bit more from day-to-day outdoor use. Each of these items may have a different laundry schedule to keep things clean and also avoid contributing to unnecessary wear and tear.



What is Body Odor (B.O.)?

Body odor has been analyzed in different studies and found to be comprised of volatile organic compounds including:

  • Volatile Fatty Acids (VFAs)

  • Thioalcohols

The thioalcohols are considered the most pungent of odors. This compound contains a sulfur atom and probably explains the odor.

We have a combination of eccrine sweat glands, apocrine sweat glands, sebaceous glands, and keratin on the surface of the skin along with bacteria that are not necessarily disease-causing but present on the surface. The secretions from the glands are acted on by bacteria to produce various odors.

Which bacteria live in our armpits?

The bacteria considered to be a part of our normal bio flora for the axilla include:

  • Corynebacterium

    • Cutibacterium (formerly known as Propionibacterium)

  • Staphylococcus species

To a lesser extent, Anaerococcus and Peptoniphilus have also been noted.

Can’t I just smell my clothes to figure out when they are due for a wash?

Smelly clothes are a general signal of the buildup of bacteria, sweat, keratin, dirt, and debris on your clothes. The bacteria release a smell or odor that is an indicator of their presence. So, yes, the smell associated with clothes is one way to determine when it is time for a wash. However, the smell is also an indicator of a significant volume of odor-releasing bacteria that may have been building up for some time.



How many wears can you get out of your workout shirt, shorts, and pants before washing them?

Although most laundering experts will acknowledge that it is probably best to wash workout clothes after every wear, we all know this doesn’t happen. There are several things to consider when it comes to deciding how frequently to launder:

  • How much you are sweating

  • How much friction your clothing and skin is experiencing during a workout

  • The environment you are in when exercising. For example, indoors on a yoga mat, on a bike, outside running/walking, etc.

If you are sweating quite a bit, it will likely make sense to wash after every wear. Odor-causing bacteria tend to build up in areas where sweat is concentrated and will get to work producing odors fairly quickly. If you keep wearing the same clothes without a wash, you are putting your skin at risk for exposure to these bacteria. Many of these bacteria are not directly disease-causing. However, if irritation to the skin occurs through friction or seams of clothing, the bacteria can enter the surface and inflame or infect hair follicles triggering folliculitis or yeast can begin to overgrow to increase your risk for rashes in the folds of the skin.

If your workout involves a lot of friction- cycling/spin for example- then your skin is experiencing sheering forces under the fabric. If there is a bacterial buildup on your clothes then the friction will put you at higher risk for exposure to these organisms.

If your workout involves a mat or a stationary object, the bacteria building up on your clothes plus the mats/seats will only increase your risk of exposure- especially to Staphylococcus species.

If you are not really sweating much- chill yoga or simply walk on a treadmill without really building up a sweat, it’s not unreasonable to get 2-3 uses out of a workout outfit before washing. My only caution here would be how you store your clothes when not washed between workouts.

  • Hanging the clothes to allow sweat to evaporate and dry will reduce the chances of bacterial overgrowth.

  • If you plan on rolling up your workout shirt and tossing it in a gym bag to take out a day or two later to reuse, this is not the greatest idea. This will create an environment where bacteria will thrive.

If you do not intend to wash your clothes after a workout, it may be best to air dry or hang your clothes on a hook exposed to air to limit this buildup.

For each type of workout, how many wears before washing?

Yoga (i.e., not hot yoga): 2-3 wears would be quite reasonable as long as you are not sharing mats with other people. Washing your mat down with a disinfectant spray is important to practice at the very least. The other benefit here in terms of not over-washing yoga gear is that you are less likely to wear out the spandex or elastic element too quickly. Overwashing with other garments can start to stretch these out of shape.

Hot yoga: one wear. This is the perfect environment for bacteria, fungi, and yeast to overgrow. It’s almost impossible to leave a hot yoga studio without sweating from head to toe- even if you didn’t work out!

High-Intensity Interval Training (HIIT): HIIT involves both movement and equipment. By exposing our skin to both excess sweat and potential organisms living on equipment, it is best to reduce the overall bacterial exposure by washing it after every use.

Pilates can be strenuous but not necessarily excessively sweaty. Two uses are reasonable with the exception of Pilates reformer. The machinery here that may be shared needs to be considered. Bacteria on the platforms and seats can increase our risk of exposure.

How much wear can you get out of a sports bra before washing it?

Sports bras are in the closest contact with our skin and should be washed after every use. There are a number of issues I see routinely from not doing so. The most common would be repetitive friction coupled with sweat accumulation that can contribute to the maceration of the skin. This creates an environment for yeast to overgrow under the breasts. The result is a painful, sore, and very sensitive rash. This can often be avoided by taking the right measures to reduce exposure to bacteria and yeast and avoid sweat accumulation from contributing to the problem.

How many wears can you get out of socks before washing them?

The frequency of washing socks can vary from person to person. The factors to consider here are :

  • Baseline levels of sweat for the individual

  • Excess sweat buildup from activity

  • Underlying health conditions such as diabetes where foot care is essential

  • Underlying tendency to develop swelling or edema of the feet or legs that can place the area at a higher risk for infection

  • The material the sock is made from

In general, it may be best to wash after each use if unsure. However, if the socks are simply worn for warmth around the house with little activity that accompanies the use and little risk for sweating or underlying diseases, it may be possible to get 3-4 uses out of a pair before washing.

Why is washing workout clothes so important?

I have diagnosed and treated thousands of patients for:

  • Recurrent yeast infections

  • Vulvar pruritus (itching)

  • Lichen sclerosis

  • Vulvodynia (pain)

  • Hyperhidrosis (excess sweating)

  • Recurrent folliculitis (hair follicle infection)

  • Staphylococcus carrier state

  • Hidradenitis suppuritiva (draining cysts)

  • Cellulitis

  • Tinea corporis

  • Tinea cruris

  • Tinea pedis

  • Erythrasma

  • Seborrheic dermatitis

  • Candidiasis

  • Pityrosporum folliculitis

  • And much more!

I really sat down and reviewed the research on the impact of clothing on causing or contributing to these conditions as well as helping to manage the treatment of these conditions. Understanding the role of clothing in your overall skin health can avoid triggering uncomfortable skin conditions.

How exactly does clothing contribute to skin rashes?

Clothing can contribute to or help manage skin rashes based on how it affects your skin directly through friction or moisture management and indirectly by impacting the bio flora on the skin.

Clothing can:

  • Hold onto sweat based on the weave of the fabric or material

  • Wick moisture away from the skin based on the construction of the textile through capillary action

  • Irritate the skin at points of friction or rubbing against the material or seams

  • Have antimicrobial agents embedded into the textile or coated on the surface for odor management

  • Influence the volume of sweat produced based on the breathability of the textile

Considering the type of textile chosen, the fit, and the style can influence the ability of your skin to navigate its needs more effectively.

Any advice on textiles to consider when it comes to sweating?

When it comes to textiles and clothing consider how each fiber interacts with sweat.

  • Cotton: Cotton tends to absorb sweat and moisture and hold it in the fabric. Although cotton is highly breathable and more comfortable to wear when sweating, the moisture-absorbing property makes it tougher to re-wear without washing after each use.

  • Lycra/nylon: Lycra tends to be moisture-wicking. It pulls sweat and moisture away from the skin. Most workout wear has an element of lycra simply because it does not show the sweat visibly in the fabric. The moisture-wicking ability may allow this textile to go 2-3 wears before washing.

  • Smart wool: Smart wool is fascinating as it allows our skin to breathe while moisture-wicking. It is said to release sweat as vapor once in the fabric. Although many hear the word ‘wool’ and do not think of this as ideal for sweating, it is worth considering. 2-3 uses before washing are not unreasonable.

Are there other factors that affect how much we sweat?

Sweating can vary quite a bit based on both internal and external factors.

Internally, sweating can be triggered by :

  • Hormonal changes

  • Foods we eat

  • Caffeine

  • Illnesses

  • Genetics

  • Age

Externally, sweating is really influenced by the temperatures around us based on:

  • Macroscopic environment: Environmental temperature outdoors and indoors

  • Microscopic environment: The temperature closer to the skin’s surface is influenced by the interaction of clothing and our body’s heat.

In practice, we classify the degree to which we sweat based on how effectively we can manage it with simple interventions and how much it affects our day-to-day life.

  • Light sweaters are those that can manage their sweat effectively with simple interventions such as over-the-counter antiperspirants under most conditions. Their sweat does not impact their day-to-day life.

  • Moderate sweaters are those that can manage their sweat under most conditions but will find that they are aware of their sweat. Some activities, even when not strenuous, will trigger their sweat and make them feel occasionally uncomfortable. They may still be able to use over-the-counter options but may start to consider alternative approaches.

  • Heavy sweaters are those that simply cannot find simple interventions to help manage their sweat. It impacts their day-to-day lives, it impacts their social lives, and it affects the choices they make when they dress. These people often, (hopefully) find their way to their Dermatologist to learn about prescription options and treatments to help.

Lastly, we have discussed bacteria and yeast- what about viruses on our clothes?

Over the past couple of years, much has been discussed about viruses and their ability to live on surfaces. Viruses do not emit an odor themselves and are not usually considered when discussing antimicrobials, especially as it pertains to textiles, as the focus tends to be odor-causing agents.

There are studies that have shown that viruses have been found on washed textiles, on the wall of washing machine tubs, on shelves, and on other surfaces. I deal with a number of different types of viruses that we need to routinely protect ourselves from - HPV, molluscum, hepatitis C, and now COVID.

As a dermatologist and the wife of an orthopedic surgeon with 3 kids, I have strict laundry rules to avoid viral spread. Any clothes my husband and I wear to work get washed separately in hot water. Studies have shown that a water temperature of 40°C can kill viruses. I have never figured out a way to check the water temp in my laundry machine since I have a front-loading machine. So as an added safety measure, if concerned about a particular exposure in our clothing, we may run one extra rinse after the clothes have been removed from the washing machine with hot water and bleach as this has been shown to be another effective means to potentially kill viruses that could linger. Of course, I try to limit this type of wash to once per week for the clothes that must be washed this way to avoid wasting water too!

Please remember to not wash potentially infected clothes by hand. You may risk the spread of the viruses you are trying to avoid this way. It is also not likely to be able to achieve water temperatures as high as 40°C with your bare hands.


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