Menstrual pads are multi-layered products designed to absorb and contain menstrual fluid, typically consisting of a top sheet, an absorbent core, and a leak-proof back sheet. For many users, the experience of wearing a pad is frequently accompanied by a persistent feeling of discomfort. This common issue stems from a complex interplay of the product’s chemical composition, its physical structure, and the resulting environmental changes it imposes on the sensitive vulvar skin. The reasons behind this discomfort relate to the materials used, the mechanics of the design, and the resulting microclimate created near the skin.
Irritation Caused by Materials and Chemicals
The materials that make up a disposable pad can provoke skin reactions, leading to various forms of contact dermatitis. Many pads utilize synthetic fibers like polyolefins, polyester, or polypropylene for their top sheets and backings, which can sometimes be abrasive or chemically irritating to sensitive skin. These materials may trigger irritant contact dermatitis, a non-allergic rash caused by direct damage to the skin barrier from a substance.
Chemical additives used in the manufacturing process are another source of irritation. Fragrances, which are added to mask odors, are common sensitizers and can cause allergic contact dermatitis in some individuals. Certain dyes used to color the pad can also act as allergens, leading to redness, itching, and inflammation upon prolonged contact.
The adhesive strip that secures the pad to underwear contains various chemical compounds, some of which may be problematic. Chemicals like colophonium (rosin), methacrylates, or preservatives such as methyldibromo glutaronitrile (MDBGN) have been identified as potential allergens in the pad’s glue. When these substances come into contact with the skin, especially in the highly permeable genital area, they can trigger a hypersensitivity reaction.
Discomfort Related to Physical Design and Fit
A significant portion of pad-related discomfort is mechanical, caused by the product’s physical interaction with the body during movement. The rigid structure and overall bulkiness of many pads can lead to an unnatural feeling and movement restriction, which can be particularly bothersome during physical activity. When a pad is too thick or stiff, it resists conforming to the natural curves of the body, creating pressure points and causing it to bunch up or shift.
Chafing, or friction dermatitis, is one of the most frequently cited complaints, resulting from the pad repeatedly rubbing against the inner thighs and vulvar skin. This friction is often exacerbated by the edges and wings of the pad, which are designed for security but can act as abrasive surfaces during walking or exercise. The movement creates micro-abrasions on the delicate skin, leading to soreness, redness, and a burning sensation.
An improper pad size or absorbency level can contribute to mechanical discomfort. A pad that is too small may shift excessively, increasing friction and the risk of leakage. Conversely, one that is too large can feel bulky and bunch uncomfortably between the legs.
The Impact of Heat and Moisture Retention
The construction of many disposable pads creates a warm, occlusive environment that significantly alters the natural microclimate of the vulvar skin. The leak-proof back sheet, typically made of a non-breathable polyethylene film, prevents moisture from escaping as vapor. This lack of ventilation traps body heat and humidity, causing the skin temperature under the pad to increase, sometimes by more than a degree Celsius compared to uncovered skin.
The retained moisture softens the outer layer of the skin, a process known as maceration. This compromises the skin’s barrier function and makes it more susceptible to friction and chemical irritation.
Studies have shown that wearing a conventional pad can raise the skin’s surface pH from its natural acidic level of approximately 5.2 to a more alkaline 5.8. This increase in pH disrupts the balance of the natural microbial flora.
The resulting warm, moist environment and elevated pH create ideal conditions for the overgrowth of certain microorganisms, which can lead to inflammation and infection. Rashes, including those caused by yeast or bacteria, become more likely when the skin’s defense mechanisms are weakened. The feeling of dampness and heat itself is a major contributor to the overall sensation of discomfort.