Flex · Menstrual Cups
Flex Menstrual Discs
Lower concern; silicone-based period product with no known PFAS risk, but brand provides no transparency.
Flex menstrual discs are made from medical-grade silicone, a material not typically associated with PFAS content. The brand does not publicly disclose PFAS testing or claims regarding forever chemicals.
Shop Flex on Amazon →Material
Medical-grade silicone
Brand disclosure
Brand is silent on PFAS
Lab data
No public lab test
Why this grade
Category baseline
period care is a category where PFAS exposure is more common.
No PFAS disclosure
No public statement about PFAS in this product.
Safe base material
Made from a material with no inherent PFAS use (ceramic, mineral, or natural fiber).
The full breakdown
What it's made of and why it matters
Flex Menstrual Discs are constructed from medical-grade silicone, a synthetic polymer known for chemical stability and low leaching potential in body-contact applications. Medical-grade silicone does not contain BPA, BPS, or phthalates by design, and does not degrade into microplastics under normal use conditions (room temperature, no heating). Unlike latex or lower-grade rubbers, this material is chemically inert at vaginal pH and body temperature, making it safer for prolonged internal contact than many cup competitors.
The brand's record and disclosure
Flex has not published third-party safety testing, material certifications (ISO 10993 biocompatibility), or PFAS testing results; this silence is a notable transparency gap even for a direct-to-consumer brand. The company markets medical-grade silicone as its safety anchor but does not disclose supplier chain vetting, manufacturing facility standards, or independent lab verification. No major product recalls or health complaints have entered public record for Flex Menstrual Discs. The brand's reticence on PFAS and material sourcing does not indicate a known problem, but it limits independent verification.
How it compares in its category
Flex Discs occupy a middle ground between traditional cups (firmer silicone, lower cost, more studied) and disposable disc alternatives (plastic/polymer, single-use waste). Medical-grade silicone menstrual discs are generally safer than lower-cost silicone cups from unvetted suppliers, which may use industrial-grade silicone with higher trace contaminant risk. Compared to plastic-based products or latex-free rubber, Flex's material choice avoids phthalate and latex allergen pathways entirely, positioning it as a low-chemical-hazard option in the reusable category.
If you buy it
Wash with unscented soap and water before first use and after each cycle; avoid oil-based lubricants and harsh cleaners that may degrade silicone over time. Do not boil or autoclave (high heat can compromise seal integrity and surface texture); gentle hand-washing or cold-water soaking is sufficient. Replace after 2-5 years of use or if you notice tearing, sticky residue, or persistent odor that cleaning does not remove. Store in a breathable pouch away from direct sunlight and heat; silicone can absorb odors and minor staining (which does not affect safety) is normal.
Beyond PFAS: other things we checked
Established hazard classes for this product type, assessed from public information. These never change the PFAS grade; a Likely flag caps the Verdict at “Buy with care.”
Silicone degradation and particulate shedding
Medical-grade silicone is stable under normal use, but micro-tears from insertion friction or long-term flexing may shed trace amounts of silicone particles. No clinical data on Flex products specifically; risk remains theoretical and lower than lower-grade elastomers.
Allergen/irritant sensitivity to silicone additives
Silicone manufacturing may involve trace residual catalysts or plasticizers; individuals with silicone sensitivity (rare) may experience localized irritation. Flex has not published processing residue specifications or patch-testing data.
Bacterial colonization from improper cleaning
Any reusable menstrual device poses low but documented risk of bacterial overgrowth if not rinsed thoroughly between cycles. This is a use-hygiene issue, not a material defect; proper care mitigates risk significantly.
Heavy metals in silicone pigments (colorants)
Medical-grade silicone colorants are typically non-toxic, but Flex has not disclosed pigment sourcing or cadmium/lead testing. Risk is not established in literature for this product class.
Off-gassing or odor from manufacturing residues
New silicone products may emit subtle odors from curing agents or mold release compounds; this typically dissipates within one wash cycle and does not indicate toxicity. Flex does not specify post-manufacturing processing or off-gassing duration.
What we don’t know
This grade is a model-based estimate from public materials, coatings, and brand disclosure at 72% confidence. It is not a lab result.
No independent PFAS lab test is on record for this exact product. A lab test could move the score in either direction.
The brand has not made a specific, verifiable PFAS-free statement, so part of this score reflects that missing disclosure rather than a confirmed material.
Formulations and coatings change between production runs. Always check the current label before buying.
Safer alternatives in Menstrual Cups
Aisle
DIVA Cup Model 2
Medical-grade silicone (body); no Teflon-type coating or Teflon-family coating coatings
Lower-concern menstrual cup; silicone construction and PFAS-free commitment make it a reasonable choice.
✓Verified PFAS-free by a third party
Ruby Cup
Steriliser
Stainless steel heating chamber with silicone/plastic components
Lower-concern menstrual cup sterilizer; stainless core typical for appliances, but silicone/plastic parts unspecified, contact brand for material detail.
⚠Risky category by default
Ruby Cup
Steriliser Purple
stainless steel steriliser/heating element
Lower PFAS concern; no high-risk coatings typical of this product category.
⚠Risky category by default
More menstrual cups grades
How we score: every product runs through the same public 0–100 rubric based on materials, coatings, brand disclosure, lab findings, and recalls. See the full methodology → Spotted a mistake? Report an error.