# Menstrual Cups & Discs

Pick cup or disc first: a cup seals by suction below the cervix; a disc sits behind the pubic bone with no suction, so it works through sex and does not tug on an IUD on removal. Then size by cervix height, not age, and pick capacity by flow. Both wear up to 12 hours.

## How it works

Both forms collect flow instead of absorbing it. A menstrual cup is a flexible bell that you fold, insert, and let pop open low in the vagina; its rim forms a seal against the vaginal wall by suction, which is what keeps it in place and what you must release before pulling it out. A menstrual disc is flatter and sits higher, tucked into the fornix (the pocket behind the cervix) and wedged behind the pubic bone; it holds position by fit, not suction, so it does not press on the vaginal walls and stays put during penetrative sex. Both are FDA Class II devices (21 CFR 884.5400, product code "Cup, Menstrual") made of medical-grade silicone, natural rubber latex, or, for single-use discs, a medical-grade polymer blend. Capacity and fit depend on cervix height and flow, not on body size generally. [1] [2] [3] [5] [7]

| Family | What it is | Suits |
|---|---|---|
| Reusable silicone cup | A bell-shaped cup, boiled or wiped clean and reinserted, rated for about 10 years. | Anyone comfortable with suction removal and wanting the lowest cost per period. |
| Reusable silicone disc | A flatter ring that sits behind the pubic bone with no suction; rated for about 10 years like the cup. | Buyers who want period-compatible sex, have an IUD, or find cup suction uncomfortable to remove. |
| Single-use disc | A disc-shaped collector made of a medical-grade polymer blend instead of silicone, discarded after one wear. | Travel, a first try before buying reusable, or avoiding cleaning between changes. |

## How an expert narrows the choice

```mermaid
timeline
  section 1 · Cup or disc
    cup : ask Firmness, Removal grip
    disc : ask Reusable or single-use : skip Firmness
  section 2 · Size
    Low cervix, average, or high cervix (or after birth)?
  section 3 · Flow band
    Light to normal flow, or normal to heavy?
```

1. **Cup or disc.** A menstrual cup, or a disc?
   Cups seal by suction below the cervix; discs sit behind the pubic bone with none. That single difference decides whether sex and IUD removal are a concern, and whether firmness and stem type matter at all.
   If cup: ask Firmness, Removal grip.
   If disc: ask Reusable or single-use; skip Firmness.
   Skip if already known: an earlier answer naming cup or disc, a query that already says 'menstrual cup' or 'menstrual disc'.

2. **Size.** Low cervix, average, or high cervix (or after birth)?
   Cervix height, not age or general body size, decides which SKU fits; brands' own size charts key on this plus childbirth history, and it narrows every product line to one or two sizes.
   Skip if already known: an earlier size answer in this session, a stated brand and size (e.g. 'Saalt Regular').

3. **Flow band.** Light to normal flow, or normal to heavy?
   This sets how often the product needs emptying and which capacity tier to show; it is independent of cervix height, since a low cervix with a heavy flow still needs a high-capacity product.
   Skip if already known: an earlier flow answer in this session.

## What to surface

### Cup or disc

Whether the product is a bell-shaped cup that seals by suction, or a flatter disc that sits behind the pubic bone with no suction. This decides the removal technique (release suction vs. hook a finger behind the pubic bone), whether the product stays in during sex, and whether it needs caution around an IUD. The FDA clears both under the same device code, so the catalog is the only place this split is made explicit. [4] [5] [3]

Values: cup, disc.
Question to ask: A menstrual cup, or a disc?

Used as: top-level split, filter. Data: on the listing, backfill cost none. Look for it as: Almost always in the product title or category breadcrumb.

### Flow band

Whether the product is sized for light-to-normal flow or normal-to-heavy flow, as stated on the brand's own size chart. This is the second, independent axis of fit: a buyer with a low cervix and a heavy flow still needs the higher-capacity end of the line, not the smallest SKU. It is what actually limits how long a buyer can go between changes. [6] [7]

Values: light to normal flow, normal to heavy flow.
Question to ask: Light to normal flow, or normal to heavy?

Used as: top-level split, filter. Data: needs research, backfill cost low. Look for it as: Stated on brand size-chart pages as a flow descriptor next to each SKU; not on retail listings.
One lookup per brand's size-chart page.
Chart: Cervix-flow size map.

### Size

The SKU's size label (small, regular, or teen), chosen by the buyer's cervix height and, often, whether they have had a vaginal birth. A cup or disc that is too long for a low cervix pokes and feels wrong; one too short for a high cervix can leak or be hard to reach for removal. Every brand in this research keys its size chart to this one factor, with childbirth history as a secondary nudge toward the larger size. [6] [7] [4]

Values: low cervix, average, high cervix or after birth.
Question to ask: Low cervix, average, or high cervix (or after birth)?

Used as: top-level split, filter. Data: needs research, backfill cost low. Look for it as: The size itself (small/regular/teen) is a listing field, usually a variant selector; the cervix-height guidance that maps to it sits in a 'size chart' or FAQ page, not a structured field.
Every brand researched publishes its own size chart on its product or FAQ page; backfill is one lookup per brand line, reused across that brand's SKUs.
Chart: Cervix-flow size map.

### Material

What the device is made of: medical-grade silicone, natural rubber latex, or, for single-use discs, a medical-grade polymer blend. Latex is a hard filter for anyone with a latex allergy, and it is the only material here with a well-known allergen risk. Silicone and the disposable polymer blend are both tested to ISO 10993 biocompatibility on the brand pages checked here, but they are chemically different, which is the real difference between a reusable and a single-use product, not just the wear count. [4] [5] [6]

Values: medical_grade_silicone, natural_rubber_latex, medical_grade_polymer_blend, other.
Question to ask: Any latex allergy?

Used as: filter, shown on the card. Data: needs research, backfill cost low. Look for it as: Stated in a 'Materials' or 'Ingredients' section on almost every brand page seen in this research; not confirmed as a structured retail-listing field.
One lookup per brand's product page, reused across that brand's SKUs.

### Reusable or single-use

Whether the product is cleaned and reinserted for years, or discarded after one wear. This is the biggest cost and waste lever in the category: a reusable product's per-period cost falls to a fraction of a single-use disc's within a few cycles, but it requires boiling or another sanitizing step between periods, which a single-use disc never does. [4] [5]

Question to ask: Reusable for years, or throw away after one wear?

Used as: filter, shown on the card. Data: on the listing, backfill cost none. Look for it as: Stated plainly in the title ('reusable' or 'single-use'/'disposable').

### Firmness

How stiff the silicone is, from soft to firm, on a scale the community itself says has no agreed numeric measure. Firmer silicone pops open on its own after insertion and holds a reliable seal through exercise, which is why brands market it to beginners; softer silicone is more comfortable for sensitive or low-cervix users but needs more practice folding it to get a full seal. Only applies to cups: it is a seal-reliability trade-off, and discs don't seal by suction. [6] [8] [9]

Values: soft, medium, firm.
Question to ask: Pop open on its own, or softer and gentler?

Used as: shown on the card, filter. Data: needs research, backfill cost low. Look for it as: Named on the brand's own product page ('Original' vs 'Sensitive', or called out as 'slightly firmer'); not on retail listings and not on a measured scale anywhere.
Usually stated directly on the brand's product page per line; where absent, the community default is 'medium.'
Chart: Firmness scale.

### Rated lifespan

How many years a reusable cup or disc is rated to last with proper care; not applicable to single-use discs. This is the number the cost-per-period math actually runs on, and it is the main thing that makes a $30 reusable product cheaper over time than a box of tampons, let alone single-use discs. [4] [6] [8]

Range: 10 to 10 years. Every reusable brand in this research states exactly 10 years.

Used as: shown on the card, sortable. Data: on the listing, backfill cost none. Look for it as: Stated as a headline claim ('lasts up to 10 years') on reusable product pages.
Null for single-use discs.

### Maximum wear time

The longest stretch before the product must be emptied, as stated by the brand. This is the safety-governing number for the whole category: the toxic-shock-syndrome caution behind every '12 hours' claim is why it exists at all, and a systematic review found the real interval should track flow, not just the brand's ceiling. [4] [6] [3]

Range: 4 to 12 hours. Brands market a flat 12-hour ceiling, confirmed on three brand pages; the 4-hour floor comes from a single systematic review (van Eijk 2019), not from any brand.
Question to ask: Emptied on a schedule, or only when full?

Used as: shown on the card. Data: on the listing, backfill cost none. Look for it as: Stated as a headline claim ('up to 12 hours') on nearly every product page.

### Between-cycle care

How a reusable cup or disc is sanitized between periods: boiling, an isopropyl alcohol wipe, or a dedicated steam/UV sanitizer accessory. A buyer who travels or shares a bathroom without a stove may rule out boiling and need the wipe or a sanitizer accessory; this is a real, recurring cost and inconvenience that a single-use disc avoids entirely. [6]

Values: boiling, isopropyl alcohol wipe, steam or UV sanitizer accessory, not applicable (single-use).
Question to ask: Can you boil water where you'll clean it?

Used as: shown on the card. Data: needs research, backfill cost low. Look for it as: Stated in a care or FAQ section on the brand's page, not structured on a listing.

### Capacity

How much the cup or disc holds before it needs emptying, in millilitres. Brands translate this into 'super tampons held' because that is the unit buyers already know; the raw millilitre figure is what actually determines hours between changes at a given flow rate. [6] [7] [4]

Range: 15 to 50 mL. Small/teen SKUs run 15 to 25 mL; regular cups about 30 mL; regular discs 50 mL. Both the 15 mL and 50 mL endpoints come from one brand (Saalt); Flex Cup's largest SKU only reaches 30 mL.

Used as: shown on the card, sortable. Data: needs research, backfill cost low. Look for it as: On the brand's size-chart page next to each SKU; rarely on a retail listing.
One lookup per brand's size-chart page, reused across that brand's sizes.
Chart: bar length per SKU.

### Removal grip

What the buyer pinches or hooks to remove it: a stem, a ring, a ball, a trimmable stemless base on a cup, or a finger notch on a disc rim. A stem that sits too low pokes; one that's too high is hard to reach. Several brands let you trim the stem; a pull-tab (Flex Cup) is pitched specifically at first-time users who find pinching a stem awkward. [4] [6] [7]

Values: stem, ring, ball, stemless, pull-tab, finger notch (disc rim).

Used as: shown on the card. Data: needs research, backfill cost low. Look for it as: Usually shown in the product photos and called out as a named feature in the description; not a structured retail-listing field, confirmed only on brand pages in this research.

### FDA-registered

Whether the specific brand's device is cleared through the FDA as a Class II 'Cup, Menstrual' device (21 CFR 884.5400). This is a real safety floor for a device worn internally for hours, and it is not reliably visible on a retail listing — a buyer has to trust the brand's own claim or check the FDA's own database. Every major brand researched here states it; off-brand imports are the case where it's worth checking. [1] [2] [6]


Used as: shown on the card, filter. Data: needs research, backfill cost medium. Look for it as: Sometimes stated as 'FDA registered' on the brand's own page; never structured on a retail listing.
Checked once per brand against the openFDA 510(k) database (product code HHE) rather than per SKU; limit active backfill to the top-selling brands and treat the rest as unknown rather than assuming registration.

### Rim diameter

The width of the cup's or disc's rim in millimetres, as given on the brand's own size chart. This is a headline comparison axis in its own right, alongside capacity: the community's own comparison chart sorts cups by length and diameter as well as capacity, and a buyer moving between brands matches diameter, not just mL, to what already fits. [6] [7]

Range: 56 to 70 mm. Saalt's cups run 65-70mm across its three sizes; its discs run narrower, 56-66mm.

Used as: shown on the card, sortable. Data: needs research, backfill cost low. Look for it as: Stated on the brand's own size-chart page next to each SKU; not on retail listings.
One lookup per brand's size-chart page, reused across that brand's sizes. Flex Cup's page gives a second-dimension figure per size (e.g. '43mm x 46mm') that is not clearly labeled diameter vs. length, so it is not used as a source for this facet's range.
Chart: bar length per SKU.

## Numbers worth computing

| Metric | Formula | Why |
|---|---|---|
| Cost per period (USD) | `reusable ? price / (lifespan_years * 12) : price_per_unit` | A $30 reusable cup rated for 10 years and one period a month works out to about $0.25 a period; a single-use disc sold 12 to a pack at $16.49 is about $1.37 a period if one disc covers one cycle. The 12-periods-a-year assumption is mine, not a sourced constant, and should be shown as an assumption rather than a fact. [4] [5] [6] |
| Super tampons held (tampons) | `capacity_ml / 10` | Brands market capacity against the super tampon a buyer already knows rather than millilitres. Four brand data points (Flex Cup, Saalt Cup, Saalt Disc) cluster at 8 to 11 mL per super tampon, so dividing by about 10 mL recovers the number the brand's own listing already states, without a buyer needing to know what a millilitre of flow looks like. [4] [6] [7] |

## What you give up

- A firmer cup pops open on its own and holds its seal through exercise, which is why brands market it to beginners. A softer cup is gentler on a low cervix or sensitive anatomy but needs more practice folding it to get a full seal. [6] [8] Board branch: "See more soft, beginner-comfort cups".
- A disc avoids suction entirely, so it does not tug on an IUD and can stay in during sex, but removal means hooking a finger behind the pubic bone rather than pinching a familiar stem; a systematic review found cervical-type cups needed professional removal help far more often than bell-shaped cups (47 cases vs. 2). [3] [7] Board branch: "See more sex-compatible, IUD-friendly discs".
- A reusable cup or disc costs a fraction per period within a year or two, but it has to be boiled, wiped, or steamed between cycles. A single-use disc skips that step entirely and costs more every single period. [6] [5] Board branch: "See more low-maintenance single-use discs".

## How to draw it

**Cervix-flow size map** (two axis map, shows Size, Flow band). Plots cervix height against flow band so a buyer sees which single SKU fits both at once, the way every brand's own size chart already lays it out, instead of reading two separate text descriptions. Used today by Saalt and similar brand size-chart pages already pair a cervix-height column with a flow-band column per SKU.. [6] [7]

**Firmness scale** (scale, shows Firmness). A single soft-to-firm line lets a buyer see at a glance where a cup sits relative to the 'Original vs. Sensitive' or 'firmer vs. softer' lines brands already sell in pairs. This is a proposal, nobody draws it this way yet. [9]

## Words you will meet

- **Fornix**. The pocket of space behind the cervix, where a disc sits instead of below the cervix like a cup.
- **Cervix height**. How far up the cervix sits, checked by reaching a clean finger in until you feel it; the main thing that decides which size fits.
- **IUD**. An intrauterine device, a small T-shaped contraceptive placed in the uterus; cup removal's suction has been linked to case reports of it shifting position.
- **Suction seal**. The vacuum a cup's rim forms against the vaginal wall, which must be broken with a finger before the cup is pulled out.
- **Toxic shock syndrome (TSS)**. A rare but serious bacterial illness linked historically to high-absorbency tampons, which is why cups and discs carry a maximum wear-time caution even though reported cases are rare.
- **ISO 10993**. The standard medical devices are tested against to show their materials don't harm the body they touch.
- **Class II device**. An FDA risk category for medical devices that need specific controls to be considered safe, one step above the lowest-risk Class I.
- **Super tampon equivalent**. The way brands state capacity, by how many super-absorbency tampons' worth of flow the product holds, instead of millilitres.

## Where we made a call

- Firmer silicone trades comfort for a more reliable seal and easier opening; softer trades the reverse. (confidence medium). Two brands (Saalt, Lena) independently sell a firm and a soft line with this exact framing; no independent lab measurement of firmness was found, so this rests on brand marketing agreeing with each other, not a measured scale. [6] [8]
- Cup suction may dislodge an IUD on removal; a cohort study found no significant risk increase, but case reports exist. (confidence medium). Sources disagree. A retrospective cohort found no significant expulsion difference between cup, tampon, and pad users, but a case series of seven women reported dislodgement on cup removal. We side with the review's own caution (release suction first) over the null cohort result. [3]
- Menstrual cup leakage is similar to or lower than pads or tampons; no equivalent study was found comparing discs. (confidence medium). The only systematic review found covers cups, not discs, directly. Treat disc-vs-pad leakage as unverified rather than assuming it matches the cup finding. [3]
- Toxic shock syndrome with modern cups is rare, but no population-level incidence rate specific to cups exists. (confidence low). A systematic review of 3319 participants found five total TSS case reports; the lower bound of 'how often' is not computable from that number alone, and the only rate given (about 2.25 per 100,000 users a year) is from similar-material barrier contraceptives, not cups themselves. [3]
- Brands' capacity-to-super-tampon figures imply roughly 10 mL per super tampon, consistently across brands. (confidence medium). Four data points from two brands (Flex, Saalt) cluster between 7.5 and 11 mL per tampon; treated as 'about 10' rather than a precise constant. [4] [6] [7]

## References

1. [openFDA device classification: Cup, Menstrual (product code HHE)](https://api.fda.gov/device/classification.json?search=device_name:menstrual) (regulator). Supports: menstrual cups are FDA Class II devices under 21 CFR 884.5400; the official device definition: a receptacle placed in the vagina to collect menstrual flow.
2. [openFDA 510(k) clearances under product code HHE](https://api.fda.gov/device/510k.json?search=product_code:HHE) (regulator). Supports: the disc-shaped Instead Softcup was cleared under the same code as bell-shaped cups; list of cleared cup brands including DivaCup, Lunette, Meluna, Mooncup, Femmycycle.
3. [Van Eijk et al., Menstrual cup use, leakage, acceptability, safety, and availability (Lancet Public Health, 2019)](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6669309/) (academic). Supports: cup leakage similar to or lower than pads/tampons; vaginal vs cervical cup mechanism and the disc's fornix placement; wear interval of 4 to 12 hours depending on flow; IUD dislodgement case reports and a null cohort comparison; cervical-type cups need professional removal help far more often; TSS case reports are rare; no cup-specific population rate exists.
4. [Flex Cup product page](https://flexfits.com/products/flex-cup) (spec sheet). Supports: two-size chart with capacity in mL and super-tampon equivalence; medical-grade silicone material, 12-hour wear, 10-year life; pull-tab removal feature.
5. [Flex Disc product page](https://flexfits.com/products/flex-disc) (spec sheet). Supports: disposable disc ingredient panel naming a medical-grade polymer blend and ISO 10993 testing; fornix placement and 12-hour, single-use wear.
6. [Saalt Cup product page](https://www.saalt.com/products/saalt-cup) (spec sheet). Supports: full size chart keyed to cervix height, childbirth history, flow, and capacity in mL; firmness framed as easier opening vs. comfort; boiling, isopropyl wipe, or steamer as between-cycle sanitizing methods; 10-year reusable life, FDA registration claim; rim diameter per size: Regular and Small 70mm, Teen 65mm.
7. [Saalt Disc product page](https://www.saalt.com/products/saalt-disc) (spec sheet). Supports: disc size chart keyed to cervix height and flow; explicit no-suction claim and IUD-compatible marketing; finger-notch removal feature; rim diameter stated explicitly: Regular 66mm, Small 56mm.
8. [Lena Cup product page](https://www.lenacup.com/products/lena-cup) (spec sheet). Supports: a second brand's firm-vs-soft product line, confirming the firmness trade-off direction; medical-grade silicone, 12-hour wear, 10-year life.
9. Put A Cup In It menstrual cup comparison chart (enthusiast community). Supports: the community's own statement that firmness has no agreed numeric scale across brands.