Sanitary pads absorb and contain menstrual fluid, promoting hygiene. While designed to wick fluid away, the pad remains in close contact with sensitive skin. Neglecting to change a pad transforms it into a warm, moist environment where bacteria and fungi thrive. This prolonged exposure leads to issues ranging from localized skin irritation to clinical infections caused by the disruption of the natural microbial balance.
Local Skin Irritation and Discomfort
Wearing a pad for an extended period creates a localized environment characterized by increased heat, moisture, and friction against the skin. This combination is a primary cause of contact dermatitis, which manifests as redness, itching, and burning in the vulvar area. The presence of moisture from menstrual fluid, sweat, and urine weakens the skin’s barrier function, making it more susceptible to damage.
The continuous rubbing of the pad against the delicate skin of the vulva and inner thighs also results in chafing and physical irritation. Many conventional pads contain synthetic fibers, adhesives, or fragrances that can act as irritants or allergens, exacerbating skin sensitivity. The breakdown of menstrual fluid by naturally occurring bacteria on the skin surface leads to noticeable odor. This odor is a direct result of bacterial metabolism within the stagnant, warm environment.
Increased Risk of Infection
Prolonged pad usage significantly raises the risk of developing clinical infections by disrupting the delicate vaginal microbiome. The warm, occlusive environment of a saturated pad encourages the overgrowth of pathological organisms. This disruption can lead to two of the most common vaginal infections: bacterial vaginosis (BV) and vulvovaginal candidiasis (yeast infection).
Bacterial vaginosis occurs when the normal population of protective Lactobacillus bacteria decreases, allowing harmful anaerobic bacteria to flourish. This imbalance often results in unusual discharge and a persistent, fishy odor.
Yeast infections, caused by an overgrowth of Candida fungus, are also promoted by the constant warmth and moisture trapped by the pad. Symptoms of candidiasis typically include intense itching, burning, and a thick, cottage cheese-like discharge.
Menstrual blood alters the naturally acidic pH of the vagina. When combined with the occlusive nature of the pad, this creates optimal conditions for fungal growth. Excessive humidity is a known risk factor for vulvovaginitis, which includes both BV and yeast infections. Allowing blood and moisture to remain stagnant for many hours directly encourages the multiplication of these microbes.
Addressing Severe Risks and Recommended Frequency
Concerns about severe systemic infection often arise, particularly regarding Toxic Shock Syndrome (TSS). TSS is a rare but potentially life-threatening condition caused by toxins released by Staphylococcus aureus or Streptococcus pyogenes bacteria. The risk of developing menstrual TSS is primarily linked to the use of internal protection products, such as tampons or menstrual cups, especially when left in place too long.
Pads are external products and do not create the same high-risk environment for TSS as internal products, meaning the risk from pads is extremely low or non-existent. However, any break in the skin barrier from severe pad rash or chafing could theoretically introduce bacteria, which is why maintaining good hygiene remains important. TSS symptoms develop rapidly and include high fever, muscle aches, and a sunburn-like rash.
To mitigate the risks of irritation and infection, the consensus recommendation is to change a sanitary pad frequently. The standard guideline suggests changing the pad every four to six hours during the day, or every two to four hours during a heavier flow, to prevent saturation. Even with a light flow, it is not advisable to wear a pad for longer than eight hours, not even overnight. If symptoms like a persistent foul odor, severe pain, or discharge suggestive of BV or a yeast infection develop, medical evaluation is warranted for proper diagnosis and treatment.