Men who suffer from allergies such as eczema often develop a “contact” rash if their pants have elastic in the waistband, says Dr Friedmann, a consultant dermatologist at the Whittington Hospital and the Harley Street Dermatology Clinic, in London.
Blame it on the rubber in the elastic, which many people are allergic to.
“If there is rubber in the waistband and you sweat, then tiny bits of rubber sweat off onto the skin around the waist which can trigger a reaction,” he explains.
The colour of your underwear could, cause problems, too.
The compound PPD, which is used as black dye in poor quality, cheap pants, can cause a contact allergy, says Dr Friedmann. So stick to reputable brands.
Why Silk Might not be so Hot
Anywhere where the skin creases is prone to a form of dermatitis known as intertrigo, which leaves skin red and sore. In men, this is more common in the groin – it’s known colloquially as “jock itch” – and is exacerbated by the material in their underwear, says Adam Friedmann.
“Intertrigo is usually caused by a combination of eczema, a slight fungal infection (fungi particularly like warm, moist areas) and an irritant such as sweat – so men who exercise a lot may be prone to it, as too are men generally in the summer.
“To prevent it or reduce its symptoms we always recommend men wear pants made from absorbent materials such as cotton which will soak up sweat and wick it away from the skin.”
Less absorbent materials, such as silk, nylon and Lycra, can make the problem worse, especially if you choose tight, body sculpting pants made with these materials, as they keep the testicles close to the body, adds Christopher Eden, professor of urology at the Royal Surrey County Hospital, Guildford.
Because testicles are generally warm and sweaty, they can be a hotbed for fungi as they provide a warm, moist environment.
“You want that part of the anatomy to dry out easily and breathe,” says Professor Eden.
Snug pants may stop aches
Men can experience passing aches and pains in their testicles, though it’s not known exactly why this happens. Indeed Professor Eden describes it as a ‘significant enigma in urology’ which usually disappears just as mysteriously. The problem generally affects men aged 20 to 40.
“Some men experience this regularly, while for others it occurs after ejaculation, or after sitting for a long time while driving, for example,” explains Zaki Almallah, a consultant urologist at Queen Elizabeth Hospital and BMI The Priory Hospital, Birmingham.
Wearing tighter underwear may help – although this will be down to the individual, he adds.
It would be best for men with fertility issues to avoid tight pants and choose something looser, such as boxers, to keep the testes cool
“With looser-fitting underpants the testes are less compressed, so in principle this should be less painful, but some men find that tighter underwear is preferable because it reduces movement, and therefore the impact on the testes – it is a matter of trial and error.”
Men who’ve undergone any type of testicular surgery, such as a vasectomy, are advised to wear snug-fitting pants in the days afterwards to prevent bruising or a hematoma (localised collection of blood), and to help with pain, explains Mr Almallah. The pants have a compression effect, inhibiting swelling and bleeding.
However, men who have epididymitis – inflammation of the epydidimis, the coiled tube at the back of the testicle that stores sperm – can find wearing tight underwear is painful as it can squash the area.
“The condition is generally associated with sexually transmitted infections and urinary infections – men who have inflammation in their testes should see their GP for treatment, but wearing looser pants could be more comfortable,” says Mr Almallah.
Young men with sudden, severe testicular pain should seek emergency medical attention to exclude testicular torsion, when the cord that supplies the testicles with blood becomes twisted.
What to wear for “rude” veins
Men with varicoceles, a form of varicose veins in the scrotum, may want to think carefully about their pants. Varicoceles – which affect 15% of men – can be symptomless but may cause a dull ache. They are caused by the failure of the valves inside the vein, which causes the blood to pool, stretching the walls and enlarging it.
Studies have linked varicoceles to reduced fertility – one study from the World Health Organisation involving more than 9,000 men showed that varicoceles are commonly accompanied by impaired sperm quality.
One fifth of British men don’t change their underwear every day – this raises the risk of fungal infections.
“There are theories that having varicoceles means there is more blood than normal around the testes, making them warmer, so this could affect sperm production and fertility,” explains Mr Almallah.
However, men with varicoceles that cause pain can find snug pants helpful, adds Professor Pacey.
“If they wear boxers and their testicles are hanging down and get knocked, that causes pain and local inflammation. Support from tighter pants reduces that risk. Yet, wearing tighter pants is a double whammy for their fertility risk.”
Do you need support?
Boxers don’t offer much support, but if you aren’t experiencing testicular pain such as from varicoceles, that doesn’t really matter, says Professor Eden.
“Men don’t actually need firm scrotal support for their health. After all, clothes are a relatively modern invention.”
Tight-fitting pants won’t stop the sagging linked to ageing, either. “As we age, the elastin [the stretchy component of skin] decreases, causing wrinkles and saggy skin, and this applies to the scrotum too,” explains Professor Eden. “But supportive underwear won’t change that.”
When it comes to sport, support may be down partly to keeping things under control.
A spokesman from British Athletics says distance runners tend to prefer wearing ‘split shorts’ – shorts with a netted lining, similar to swimming trunks – with no pants underneath, because this gives support and allows the area to breathe, with the comfort of wearing only one garment.