Using a menstrual cup is often described as liberating, but an unpleasant odor emanating from the medical-grade silicone can be frustrating. This smell is a common issue that does not mean the cup is ruined or that there is an underlying health problem. The odor is typically a sign of residue buildup and bacterial interaction, which is a fixable challenge with proper cleaning and maintenance. Addressing the smell requires understanding its source, applying remedial deep-cleaning methods, and adopting preventative habits.
Identifying the Source of the Odor
The primary reason a menstrual cup develops an odor is the formation of biofilm, a biological layer. Biofilm is a collective of microorganisms, such as bacteria and fungi, that adhere to the surface and encase themselves in a protective, sticky matrix. This layer traps proteins and organic residues from menstrual fluid, which then break down and cause the persistent, often sour or metallic smell.
The material of the cup itself can also contribute to odor retention over time. While medical-grade silicone is non-porous when new, it can absorb volatile organic compounds (VSCs) and odors if it is not cleaned thoroughly or if harsh chemicals are used. These compounds are absorbed into the material’s surface, making the odor difficult to remove with a simple rinse. If the cup is not fully dried after cleaning, residual moisture creates an ideal environment for odor-causing bacteria to multiply quickly before the next use.
Restoring the Cup: Deep Cleaning Methods
To eliminate a strong, existing odor, remedial deep cleaning is necessary to break down stubborn biofilm and residue. Boiling the cup is the most effective method for sanitization. Submerge the cup completely in a dedicated pot of boiling water for five to ten minutes. Ensure it does not rest against the bottom of the pot, which can cause the silicone to burn or warp.
For persistent odors, soaking treatments can help neutralize trapped compounds. A hydrogen peroxide soak using a three percent solution diluted with an equal part of water is effective at breaking down organic matter and stains. Alternatively, use a solution of half white vinegar and half water, soaking the cup for 40 minutes to an hour. Rinse the cup thoroughly after either soak and follow up with a short boil to remove all traces of the soaking agent before reinsertion.
When restoring a smelly cup, avoid using harsh household cleaners like bleach, rubbing alcohol, or concentrated essential oils. These substances degrade the medical-grade silicone, causing it to break down and become more porous, which permanently traps odors and potentially causes irritation. Strong antibacterial and fragranced soaps should also be avoided. They can leave a residue that feeds odor-causing bacteria or disrupts the vaginal pH balance.
Preventing Future Odor Issues
Preventing future odors depends on consistent habits performed with every removal and cleaning. Always rinse the cup immediately after emptying it, starting with cold water before using any soap or warm water. Cold water prevents the proteins in the menstrual fluid from coagulating and setting residue or stains onto the silicone surface.
Particular attention must be paid to the small suction release holes around the cup’s rim, as these are common spots for trapped residue and bacterial buildup. Use a soft-bristled toothbrush designated only for the cup, or a toothpick, to gently scrub these tiny openings and the rim. Alternatively, fill the cup with water and squeeze it to force water through the holes, which can dislodge stubborn debris.
When choosing a soap for routine cleaning, select one that is mild, unscented, pH-neutral, and oil-free to prevent residue buildup. Many general-purpose soaps often contain oils or harsh chemicals that can damage the silicone, leading to greater odor retention. Between cycles, store the cleaned and fully dried cup in a breathable cotton bag or pouch rather than an airtight plastic container. This practice allows residual moisture to evaporate, preventing a damp environment where mold and bacteria can develop.