Cora · Menstrual Cups
Flex Menstrual Cup
Lower-concern product; silicone cups don't inherently require PFAS, but brand transparency is absent.
Flex menstrual cups are made from medical-grade silicone, which does not typically require PFAS coatings or treatments. However, Cora does not publicly disclose PFAS-related information or third-party testing.
Shop Cora on Amazon →Material
Medical-grade silicone (primary material)
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
The Flex Menstrual Cup is constructed from medical-grade silicone, a synthetic polymer chosen for flexibility, durability, and biocompatibility in internal-contact products. Medical-grade silicone does not require Teflon-type coating coatings, plasticizers like phthalates, or BPA to function, and is specifically manufactured to withstand repeated sterilization and prolonged internal contact. The Flex design prioritizes thin-wall flexibility over rigid structure, which is a material strength rather than a safety concern when sourced from reputable suppliers.
The brand's record and disclosure
Cora (the parent brand behind Flex) has no published safety controversies or product recalls on record for this cup. The brand does not publicly disclose third-party testing, material certification details, or explicit PFAS sourcing statements, which represents a transparency gap common among small menstrual-product companies but not evidence of contamination. Standard industry practice for medical-grade silicone cups does not typically involve PFAS, but silence on supply-chain vetting is a missed opportunity for brand credibility.
How it compares in its category
Menstrual cups made from medical-grade silicone (like Flex) occupy the safest category within the product class, avoided the plasticizer and BPA pitfalls that plagued early plastic cup designs and some competitor products using lower-grade silicone. Cups made from TPE (thermoplastic elastomer) or unspecified silicone carry higher risk of leaching; Flex's explicit medical-grade designation aligns it with category leaders like Saalt and OrganiCup in material choice. The absence of documented testing or third-party certification is typical even among premium competitors.
If you buy it
Sterilize by boiling for 5-10 minutes before first use and monthly thereafter; do not use water hotter than 212F/100C as extreme heat may degrade silicone over many years, though short-term boiling is safe. Replace the cup every 2-5 years if the silicone becomes visibly sticky, stained, or develops an odor resistant to vinegar soaks, as these signal polymer degradation. Store in a breathable pouch, not airtight plastic, to prevent bacterial growth; rinse daily with water and mild soap, and inspect the drainage holes for blockages monthly.
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 odor retention
Medical-grade silicone is durable but not permanent; after 2-5 years of use, the polymer can become sticky or develop odors that harbor bacteria. This is a wear issue rather than acute toxicity, but signals the product has reached end-of-life and should be replaced.
Bacterial growth if improperly stored or maintained
Silicone itself does not leach harmful substances, but the internal environment of the cup can harbor pathogens if stored in airtight containers, left wet, or rinsed inadequately. Risk is low with proper hygiene but real with neglect, especially if used longer than the recommended 12-hour duration before removal and cleaning.
Allergen or irritant reactions to silicone (individual sensitivity)
Medical-grade silicone is hypoallergenic by design and no adverse reactions specific to the Flex cup are on record. Rare individuals with silicone sensitivity exist but are typically identified by dermatologists; for them, alternative cup materials (glass or natural rubber latex-free polymers) would be necessary.
Lack of third-party material certification
Cora does not publicly report ISO 10993 biocompatibility certification or independent lab analysis of the silicone formulation. While the stated medical-grade claim is likely honest, absence of published certification creates uncertainty about supplier vetting and additive composition that competitors like Saalt and Lunette disclose.
PFAS in silicone sourcing (indirect risk, category-level)
Silicone menstrual cups do not inherently require PFAS in their formulation; however, Cora's silence on supplier PFAS policies means contamination via manufacturing or mold-release agents cannot be ruled out without testing. This is a transparency and supply-chain governance issue, not a material-level defect.
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.