A viral TikTok has been telling women to toss their underwear every six to nine months, warning that anything older could be unhealthy. The internet reacted exactly how you would expect. Some people were shocked. Others admitted they still own pairs from years ago. Many simply wondered if they had been doing hygiene wrong all along. In fact, a report by The Asian News Hub also echoes the same claim that underwear must be changed in every six to nine months. Health and Me ran a fact check to see whether there is a mandate on when to change your underwear and here is what we found:Also Read: US FDA's New Framework Calls For Speeding Up Approvals For Rare Disease Therapies Speaking to Today.com, Dr. Jen Gunter, OB-GYN and author of The Vagina Bible, pushed back strongly against the claim on social media. She explained that underwear does not suddenly become dangerous after a specific time period.The idea, she said, reflects cultural anxiety around the vulva rather than science. Many people grow up hearing the vagina is fragile, dirty, or constantly at risk of infection, which fuels rigid hygiene rules that are not medically necessary.Doctors agree there is no expiration date. “There is no rule that says after six months you must replace your underwear,” Dr. Chavone Momon-Nelson, an OB-GYN at UPMC in Pennsylvania, told Today.com. She added that social media often turns suggestions into hard rules, even when evidence does not support them.However, Dr Shirin Lakhani of Elite Aesthetics told Independent that underwear is in close contact with skin and intimate areas and could take in a lot of dead skin and bacteria, including naturally occurring ones and the harmful ones, which could lead to infection. She said that even regularly washing your underwear in a washing machine "won't always rid it completely of bacteria such as E.coli."Another gynecologist Narendra Pisal at London Gynaecology suggests a 50-wash rule for discarding underwear.What Actually Matters For Vaginal HealthInstead of the age of underwear, doctors say cleanliness and dryness are what really affect health.Dr. Christine Greves, who practices at the Center of Obstetrics and Gynecology in Orlando, explained that clean underwear made from breathable fabric is usually sufficient. Cotton is commonly recommended because it allows airflow and reduces moisture buildup.Damp or sweaty underwear can irritate skin and increase the chance of infection, but that problem has nothing to do with how long you have owned the garment. It has to do with whether it is clean and dry.Momon-Nelson, DO, who specializes in obstetrics and gynecology and is board-certified in obstetrics and gynecology by the American Osteopathic Board of Obstetrics & Gynecology, added that normal washing removes bacteria effectively, especially in warm or hot water. Regular laundry habits are enough for hygiene in most cases. The Yeast Infection FearOne persistent fear behind the viral claim is yeast infections. Some believe old underwear stores fungus even after washing.Greves pointed to an older study examining whether candida could survive laundering. The research found that routine washing removed the organism and did not transmit infections when the underwear was reused.Read: Where You Get Your Rabies Shot Matters: Doctor Explains Why Rabies Vaccines Should Not Be Given In ButtocksIn other words, properly washed underwear does not act as a hidden infection source. However, constant washing, body oils, residual detergent, and dried sweat could make the underwear stiff, which could ruin its soft texture and cause chaffing. Pisal says, "If your underwear is causing chaffing, skin irritation or is torn", you may need to replace your underwear sooner.Why The Myth Keeps SpreadingExperts say the rule survives because of long-standing stigma around female anatomy. Many products and trends market special cleansers, wipes, sprays and frequent replacement routines as necessary maintenance.But medically, the vulva is simply skin. Gentle washing with soap and water externally is usually enough.That does not mean buying new underwear is bad. Comfort, fit, and personal preference matter. Replacing worn-out elastic or damaged fabric makes sense. What doctors reject is the idea of a strict timeline.As Momon-Nelson told Today.com, there is nothing wrong with enjoying new underwear. The problem begins when people feel forced by fear rather than choice.