Column · Period pads & liners
Edition 1
September 2026
The Reading Room
Free to read
Canada
Free to read · Canada
Edition 1 · Published by Periodica ·
The Reading Room · Edition 1 ·
Period School
What’s inside a period pad, layer by layer.
At a glance
Who it’s for: Anyone who has wondered what a period pad is made of, or what the words on the pack mean.
Reading time: About 8 min
On this page:
- Top to bottom
- The gel inside
- “Unscented” and “fragrance-free”
- The numbers on the pack
- How a period pad is tested
- What this is not
In three points:
- A period pad looks like one soft strip. Inside, an industry association counts up to seven parts.
- The Editor found no Canadian definition of “unscented” or “fragrance-free” for period pads.
- In Canada, each maker sets its own words, numbers and droplets on a period pad pack.
From the side that touches skin to the side that touches underwear: what each layer does, what it is usually made of, and what the words on the pack can tell you.
General information, not medical advice. For anything about your own health, talk to a healthcare provider. Where to get help
- The library mapPeriod products, explained.
- Wait. What? · UnscentedCan “unscented” contain fragrance?
- The rules, by countryWhat the number on the pack means
Editor’s Note
Dear reader,
A period pad looks like one thing. An association of the companies that make them describes it as several parts, stacked in layers. This Column follows that description from top to bottom and says what each layer is for. It judges no material and names no brand. It also reads two small words on the pack, “unscented” and “fragrance-free”, and the numbers beside them. If a period pad pack has ever puzzled you, tell the Editor; the questions become next month’s reading.
— The Editor
A period pad looks like one soft strip. Inside, the European nonwovens industry association (EDANA) counts up to seven parts: a top sheet, a layer that spreads fluid, an absorbent core, a back sheet, adhesive, a release paper and a wrapper.
Each part has a job. One lets fluid in, one spreads it, one holds it, one faces the underwear, and one keeps the period pad in place. In the industry’s own words, “Some of these components may not always be present”.
This Column goes through the parts in order, from the side that touches skin to the side that touches underwear.
Top to bottom
The top sheet. This is the layer that touches skin. The industry describes it as a cover that passes fluid down to the next layer and keeps the skin dry. It can be made of cellulose-based or synthetic fibres, or a thin plastic film. The industry names polyester, polyethylene, polypropylene, a mix of the last two, viscose or rayon, and cotton.
Glossary · Top sheet
The period pad’s skin-side cover, which lets fluid pass into the layers below.
The acquisition-distribution layer. Under the top sheet sits a porous layer. The industry describes it as taking fluid in quickly and spreading it into the core. It is made of fibres or nonwoven fabric: polyester, polyethylene, polypropylene, viscose or rayon, cotton, or cellulose pulp.
Glossary · Acquisition-distribution layer (ADL)
The layer under the top sheet that takes fluid in fast and spreads it across the core.
The absorbent core. In the industry’s words, this layer “absorbs and locks in” fluid. It is made of cellulose pulp, cotton or synthetic fibres, “with or without a super absorbent polymer (SAP)”. The section “The gel inside” explains the polymer.
The back sheet. This layer faces your underwear. The industry describes it as a layer “to prevent leakage and protect underwear”. It is a nonwoven fabric or a waterproof film. The industry names polyethylene, polypropylene and polylactic acid (PLA), also a plastic.
Glossary · Back sheet
The underwear-side layer, meant to stop leaks.
Adhesive and release paper. Adhesive holds the period pad to your underwear. It is made of synthetic resins or “hot melt” polymers, which soften with heat. Adhesive may also hold the layers to each other. A silicone-coated release paper covers the adhesive until you peel it off. On some period pads, the wrapper does that job instead.
Glossary · Release paper
The silicone-coated strip you peel off to uncover the adhesive.
Wings. The Society of Obstetricians and Gynaecologists of Canada says some period pads have adhesive “wings” that “wrap around the sides of your underwear”. One maker’s instructions say they fold under and “help hold the pad in place”.
Colour. Small amounts of ink, pigment or dye may colour some layers, to tell the parts apart.
The gel inside
Some cores contain a superabsorbent polymer, or SAP. Most SAP is sodium polyacrylate, made as granules or fibres. As it takes up water-based liquid, it swells into a gel and holds the liquid in.
Glossary · Superabsorbent polymer (SAP)
Grains or fibres, mostly sodium polyacrylate, that swell into a gel as they take up liquid.
A US FDA draft, not in force, shows how a pack might list it: “Super absorbent gel (sodium polyacrylate crystals)”, a polymer “that turns into a gel when exposed to moisture”.
This section describes what SAP does. It gives no verdict on it.
“Unscented” and “fragrance-free”
The industry association says that when a period pad is fragranced, the pack says so. That describes practice in Europe, where the association works. The Editor found no Canadian rule that says the same. The association also says some period pads and liners “may contain some odor-absorbing ingredients”.
In the United States, medical device rules define an “unscented” period pad. That category “does not include menstrual pads treated with scent (i.e., fragrance materials)”. A scented period pad has scent added “for aesthetic purposes” or “for deodorizing purposes”.
Canada is different. US rules do not apply here, and Employment and Social Development Canada says “Menstrual pads aren’t medical devices or regulated in Canada”. The Editor found no Canadian definition of “unscented” or “fragrance-free” for period pads.
So the word on the front says less than a list on the back. If the maker lists what each part is made of, that list is the place to look. A US draft guidance, not in force, recommends that period pad packs list each part’s ingredients and purpose, in order of amount.
The numbers on the pack
Period pad packs carry words, numbers and droplets. In Canada, each maker sets its own.
Canada has a standard absorbency scale for tampons, set by Health Canada, and none for period pads. “‘Super’ on a period pad and ‘Super’ on a tampon are not the same thing” explains the tampon scale. A US FDA draft guidance, not in force, says: “Absorbency range as described in 21 CFR 801.430 does not apply to pads”. That US rule sets the tampon ranges. In Europe, the industry’s droplet code covers tampons.
So on a period pad, “maxi”, “ultra” or “overnight” are the maker’s words, and the droplets are the maker’s scale. Two brands can use the same word for different things.
Read more: “Super” on a period pad and “Super” on a tampon are not the same thing.
The rules, by country: what the number on the pack means
| Canada | United States | European Union | |
|---|---|---|---|
| Tampons | Five standard absorbency words set by Health Canada, measured in grams of test fluid | Standard absorbency ranges in federal rules (21 CFR 801.430) | A voluntary industry droplet system with six classes, from the industry association EDANA |
| Period pads | No standard found; the maker’s own words and numbers | FDA draft guidance, not in force: “Absorbency range as described in 21 CFR 801.430 does not apply to pads” | None found by the Editor; the industry’s droplet code covers tampons |
Each source in its own words. The Reading Room adds no opinion.
How a period pad is tested
An industry testing guideline lists four checks for period pads. Strike-through: how fast fluid goes in. Rewet, or wetback: how much comes back to the surface under pressure. Absorbency. And adhesion: how well the period pad stays stuck. Test fluids vary, from artificial menstrual fluid to saline.
Glossary · Rewet (wetback)
Fluid that comes back to the surface when a used period pad is pressed.
The same guideline says these products “are not intended to be sterile”.
What this is not
This Column describes the parts of a period pad and the words on its pack. It does not rank materials, name brands, or say whether any ingredient is good or bad for you. Fragrance and skin, and chemicals in period products, belong to other Columns.
Next in the Reading Room: “Period products, explained.”
Drafted and checked against its sources with our proud team of AI assistants; read and signed by the Editor.
This Column is general information, compiled by the Editor from the sources listed below. It is not medical advice, and the Editor is not a healthcare provider. For anything about your own health, talk to a healthcare provider.
No rush. We like reading slowly, one short piece at a time. The articles will wait for you.
Sources the Editor read (12)
- EDANA (European nonwovens industry association), “Absorbent Hygiene Products components: PAD/LINER” (December 2019), and the page “The process of adapting to feminine hygiene: menstrual pads and liners”. edana.org
- EDANA, “What are SAP – superabsorbent polymers”. edana.org
- EDANA, “The science behind Tampons”. edana.org
- EDANA, “Guidelines for Testing Feminine Hygiene Products” (13 December 2018; no public link found).
- US FDA, draft guidance “Menstrual Products – Performance Testing and Labeling Recommendations” (October 2025, not for implementation). fda.gov
- US eCFR, 21 CFR 884.5425 and 884.5435 (scented and unscented menstrual pads). ecfr.gov
- US FDA, “Fragrances in Cosmetics” (current as of 2022-02-28). fda.gov
- Employment and Social Development Canada, “Requirements for employers to provide menstrual products in federally regulated workplaces” (modified 2023-11-15). canada.ca
- Health Canada, Guidance for the Labelling of Medical Devices, Appendices. canada.ca
- DeLoughery E et al., BMJ Sexual & Reproductive Health 2024;50(1):21–26. doi.org
- Society of Obstetricians and Gynaecologists of Canada, yourperiod.ca, “Your first period” (undated). yourperiod.ca
- A period pad maker’s instructions, “How to Use a Pad” (modified 2026-02-04). natracare.com
Maker pages are cited as sources for their own instructions; a citation is not an endorsement. Periodica may sell products from brands cited here. That doesn’t change what we write.
Date due for review
| Written by | The Editor |
| Last checked | 27 Sep 2026 |
| Next check | Mar 2027 |
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