Guides
Short, data-backed reads. Best-of picks come from the live catalog ranked by verified capacity; every number traces to a brand's published claim or a named primary source - the same discipline as the data table.
Troubleshooting
Period underwear smells after washing? Here is why, and the fix
An odor that survives the wash is usually trapped residue, not dirt. Why detergent and softener buildup holds smell, how a strip wash clears it, and how to keep it from coming back.
Updated 2026-07-02
Troubleshooting
Period underwear stains not coming out? Why, and how to fix it
Set-in stains almost always mean heat got to the blood before a cold rinse did. How to lift a stain that is still liftable, and how to tell a real stain from a harmless shadow on the core.
Updated 2026-07-02
Troubleshooting
Period underwear not absorbing anymore? How to strip wash and revive it
When a pair repels instead of absorbs, the fabric is coated - usually by fabric softener or detergent buildup. How to strip wash it back to life, and when it is simply worn out.
Updated 2026-07-02
Troubleshooting
Why is my period underwear leaking? 5 causes and the fix for each
Leaking is almost always one of five things: the wrong absorbency for your flow, the fit at the legs, wearing it past capacity, dead wicking, or too low a rise. How to tell which, and the fix.
Updated 2026-07-02
Safety
Period underwear and yeast infections: breathability and vaginal health
Non-breathable synthetics trap heat and moisture, which can raise the risk of yeast infections and irritation for some people. How to lower the risk - cotton gussets, the right absorbency, changing often - without the alarmism.
Updated 2026-07-02
Safety
Silver in period underwear: the antimicrobial question
Some period underwear uses silver (sometimes nanosilver) for odor control. What the FDA found about silver and vaginal bacteria, what has and has not been studied, and how to avoid it if you would rather.
Updated 2026-07-02
Safety
Can you get toxic shock syndrome (TSS) from period underwear?
Period underwear is an external product, so it does not carry the tampon-associated toxic shock risk. What TSS is, why internal products are the concern, and the honest caveats.
Updated 2026-07-02
Safety
Are period underwear FDA-regulated? Why there is no ingredient list
Tampons, pads, and cups are FDA medical devices; period underwear is generally sold as apparel and is not. Neither has to list ingredients - which is the root of the PFAS story. Plus the state laws changing that.
Updated 2026-07-02
Safety
PFAS in period underwear: the lawsuits, the testing, and what it actually means
What PFAS "forever chemicals" are, the Thinx and Knix class-action settlements, the independent lab testing, and how to read it honestly - what was established and what was not.
Updated 2026-07-02
How It Works
Do period underwear feel wet?
Whether period underwear feels wet when you bleed into it, why a slight dampness is normal, and when a wet feeling means you have hit the pair's capacity and should change.
Updated 2026-07-02
How It Works
Can you wear period underwear every day?
Whether it is fine to wear period underwear daily for discharge, spotting or backup - how often to change it, breathability, and when a lighter style is the right daily pick.
Updated 2026-07-02
Best Of
Best period underwear for exercise
Period underwear for movement: seamless, secure styles that stay put and stay invisible under leggings. Ranked by verified capacity, with an honest note on flow rate during a workout.
Updated 2026-07-02
Best Of
Best period underwear boxers
Boxer-style period underwear, ranked by verified capacity. Who period boxers are for, why they suit sleep and sensitive skin, and how the coverage compares to briefs.
Updated 2026-07-02
Best Of
Best high-waisted period underwear
High-waisted period underwear ranked by verified capacity in millilitres. The higher back rise is not just tummy coverage - it is where the absorbent layer needs to reach for overnight and heavy days.
Updated 2026-07-02
Best Of
Best cotton and organic period underwear
Period underwear with a cotton or organic-cotton top layer, for sensitive skin and breathability. What "cotton" does and does not mean once there is an absorbent core underneath.
Updated 2026-07-02
Best Of
Best period underwear for C-section recovery
After a C-section the waistband cannot sit on the incision. High-rise period underwear with real postpartum capacity, ranked by verified millilitres, so the band clears the scar and still holds the lochia.
Updated 2026-07-02
Best Of
Best budget period underwear
The lowest-priced period underwear in the catalog, ranked by price, with the cost-per-wear math that decides real value. Cheap up front is not the same as cheap over two years.
Updated 2026-07-02
Best Of
Best period underwear for perimenopause
Perimenopause brings sudden heavy days and spotting you cannot plan around. The highest-capacity period underwear, ranked by verified millilitres, so a flooding day does not catch you out.
Updated 2026-07-02
How It Works
What size period underwear should I get?
Period underwear is sized on your hip measurement, not your usual dress or bra size, and brands disagree, so the same body can be a M at one brand and an L at another. How to get it right the first time.
Updated 2026-07-02
Explainer
What does "Heavy" mean in period underwear?
A tier labeled "Heavy" holds about 20 to 63 mL depending on the brand - a 3x spread for the same word. What it really means, brand by brand, in millilitres.
Updated 2026-07-02
Explainer
How much do period underwear actually hold?
Brand claims run about 20 to 100 mL. The one lab test with real blood measured 1 to 3 mL before leaking. Both are true - here is how to use each.
Updated 2026-06-12
Explainer
How many tampons is Knix Heavy?
Knix counts in SUPER tampons, not regular ones. Its Heavy tier is about 4 to 7 super tampons, which works out to roughly 36 to 63 mL - more than the same number of regular tampons would suggest.
Updated 2026-06-12
Explainer
Is Thinx Super 100 ml?
Short answer: that question mixes two different Thinx numbers. Thinx dropped its old per-tier ladder; its current styles print one blanket "up to 100 mL" claim. Here is what is actually published, verified on the brand's pages.
Updated 2026-06-12
Bladder Leak
Period underwear vs. incontinence underwear: what's the difference?
They look alike and some brands sell crossover styles, but period and incontinence underwear are tuned for different fluids and labeled on different scales. When one product serves both, and when it does not.
Updated 2026-06-12
Bladder Leak
Reusable vs. disposable incontinence underwear
Washable reusable underwear versus disposable pads and pull-ups for bladder leaks: cost over time, capacity, comfort, and dignity - and exactly where each one wins.
Updated 2026-06-12
Bladder Leak
Best washable incontinence underwear for women
Reusable, washable incontinence underwear for light bladder leaks - the in-stock styles in our catalog, and an honest note on where this young category is still thin.
Updated 2026-06-12
Explainer
How many pairs of period underwear do you need?
A full cycle usually takes six to nine pairs, depending on your flow, how often you change, and your laundry routine. How to work out your own number without over-buying.
Updated 2026-06-12
Explainer
Are period underwear worth it?
The honest cost case: a higher upfront price that pays back over about two years versus disposables - if you get the absorbency right the first time. The math, and the one trap to avoid.
Updated 2026-06-12
Comparison
Period underwear vs. pads and tampons
How period underwear compares to pads and tampons on absorbency, comfort, cost over time, and convenience - and where each still wins. No brand's thumb on the scale.
Updated 2026-06-12
How It Works
Do period underwear actually work?
Yes, within their capacity - and the honest version of that answer is the useful one. What the independent lab data shows, where they work best, and the trick to getting them right the first time.
Updated 2026-06-12
How It Works
How does period underwear work?
Period underwear works through layers: a wicking top layer, an absorbent core that holds the liquid, and usually a leak-resistant barrier. What each does, and why the claimed capacity is a lab maximum.
Updated 2026-06-12
Care
How long does period underwear last?
Most brands estimate around two years or 40-plus washes with proper care. What shortens that, and the signs a pair has lost its absorbency and needs replacing.
Updated 2026-06-12
Care
How to wash period underwear
Rinse cold, wash cold on gentle, skip the fabric softener, air dry. The simple routine that keeps the absorbent layer working - and the two mistakes that wreck it fastest.
Updated 2026-06-12
Best Of
Best period underwear for teens and first periods
How to choose period underwear for a teen or a first period: which absorbency tier to start with, how sizing works, and the teen-specific styles in our catalog.
Updated 2026-06-12
Best Of
Best postpartum period underwear (reusable)
Reusable, high-capacity period underwear for postpartum bleeding (lochia), ranked by verified millilitres. How reusable pairs differ from the disposable mesh underwear hospitals provide.
Updated 2026-06-12
Best Of
Best period underwear for light days and spotting
For light days, spotting, the end of a period, or daily discharge you want a thinner, lower-capacity pair. These are the period underwear with a verified capacity of about 20 mL or less.
Updated 2026-06-12
Best Of
Best overnight period underwear
Overnight wear needs the highest capacity and the most coverage. These are the period underwear with a verified capacity of 60 mL or more, ranked by how much they hold.
Updated 2026-06-12
Best Of
Best period underwear for heavy flow
The most absorbent period underwear for heavy flow, ranked by verified capacity in millilitres - not by the word "Heavy," which means anywhere from 20 to 63 mL depending on the brand.
Updated 2026-06-12
Explainer
Why "12 tampons' worth" means 60 mL at one brand and 100 mL at another
Two brands use the identical phrase for a 67% different capacity. The receipts, the missing standard behind them, and how to compare honestly.
Updated 2026-06-11
Explainer
What AI gets wrong about period underwear absorbency
Five measurable failure modes - invented tampon math, marketing tags read as tiers, stale brand ladders, same-word-different-number tiers, claims quoted as lab facts - and the 5-question audit that catches them.
Updated 2026-06-11
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