see also:

• infertility

• apparently up to 20% of Western males go “commando” in public at least some of the time - usually for personally preference
• data is not available for women but wearing G-strings is near commando in reality
• historically, the prime purpose of underwear such as loin cloths by the Romans was to protect outerwear and reduce the frequency of washing which damaged the outerwear at a time when people owned far less outerwear than most people have in modern times - the use for modesty was a secondary benefit
• in medieval times, breathable loose linen underwear was generally preferred, presumably to reduce the risk of fungal conditions

• increased moist, humid groin environment which increases risk of tinea cruris fungal infection, and in women, also candida infection
  • risk is higher in those who are immunocompromised (including diabetics), and in those who are overweight
  • it is probably important to delay putting on underwear after a bath or swim until the groin area is quite dry, particularly in warm, humid environments
  • it may be beneficial to not wear underwear when relaxing in warm humid environments - however, when going for a walk, wearing underwear in these situations may reduce skin irritation and rashes from thigh friction on moist skin
  • if you already have fungal groin infection, then at least at home, probably should avoid perpetuating it, and ensure the groin area is dry by allowing it to ventilate adequately
  • polyester underwear is a particular issue for women in this regard, and most would advise more breathable cotton underwear
  • change underwear daily
  • see also candida fungal infection / thrush, tinea fungal infections
• potential risk of male infertility
  • see also infertility
  • this is due to chronic high scrotal temperatures which impede sperm production
  • the scrotum is designed to regulate its own temperature, but this can be impossible if wearing tight underwear - men who wear loose boxers appear to have a 25% higher concentration of sperm and 17% higher sperm count compared with those who wore tighter underwear
• sleep issues with over heating and increased risk of both of the above
  • falling asleep requires your body temperature to fall
  • sleeping under blankets, quilts, sheets (or worse, sleeping bags) will seriously reduce ventilation to your groin area and encourage a moist, warm environment which fungi love, this is likely to be further exacerbated by wearing underwear and pyjamas
  • unless there are good reasons or personal preference, probably best not to wear underwear (or pyjamas in summer) when sleeping in bed - a tee shirt or skivvy only on cooler nights is a better option
  • see also sleep hygiene
• psychologic issues of lack of freedom

• reduced soiling of clothing
  • this can be a major social issue if accidents occur in public resulting in visible soiling
  • it also means less frequent washing of clothing is needed
• supportive structure for use of female hygiene pads or incontinence pads
  • men may also need these have they have a intermittently bleeding thrombosed haemorrhoid
• potential reduced transmission of diseases from seats such as at gyms
  • many genital pathogens can remain on objects for hours and can theoretically be transmitted to another persons bare skin when the sit on it
  • these include Herpes simplex virus (HSV)
  • women are a particular issue at gyms as G strings probably do not suffice to reduce this risk and ultra-thin gym materials for gym shorts may allow pathogenic transmissions
  • this can be at least partly mitigated by ensuring seats are wiped with alcohol based antiseptics before and after use
  • note though that, as we all are well aware, underwear and even trousers do not prevent the escape of flatus gases although they probably reduce the escape of faecal pathogens during passing of flatus - perhaps.
• protection of male genitals in sports and at work
  • absence of a supporting underwear for men in these activities can increase risk of traumatic injury
• may reduce groin friction and rashes when walking on hot days
• special circumstances
  • men with scrotal varicoceles probably are more comfortable with supportive underwear
  • post-operative such as vasectomy, generally requires supportive underwear
  • post-partum generally requires use of pads and loose underwear
  • wearing “smart” underwear that detects substances or illnesses
    • Smart underwear detects flatus hydrogen: A novel wearable for long-term monitoring of gut microbial gas production via flatus ¹⁾
• modesty / high risk social circumstances
  • if your trousers accidentally tear in public and you are not wearing underwear, this could be a major embarassment
  • you may also feel embarrassed if suddenly you need hospital care - hence you grandmother's advice to always be wearing clean underwear
  • wearing short skirts without underwear may be an issue in many social situations