Cheap synthetic underwear fabrics such as pure polyester or nylon trap sweat and bacteria against the skin more than cotton underwear does.
NOT BSTOTAL BS
NOT BS — Verdict: True
Verified by Lenz ·
The Short Version
The evidence strongly supports the core takeaway that cotton underwear is generally less likely than pure polyester or nylon to hold sweat and foster odor-related bacterial buildup next to the skin. Clinical guidance and textile studies consistently favor cotton for breathability and moisture control. The main caveat is that fabric blends, knit structure, and moisture-wicking treatments can affect performance.
Caveats
The strongest direct laboratory evidence is for polyester; nylon is supported more by broader clinical guidance than by equally specific head-to-head studies.
This does not mean synthetic underwear causes infections by itself; hygiene, fit, sweat duration, fabric blend, and garment construction also matter.
A study showing more bacterial adherence to dry cotton does not contradict sweat-exposed wear conditions, which are the relevant conditions for this claim.