How To Wash Your Period Underwear + Care Guide
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Period underwear needs specific care to stay absorbent and long-lasting. The absorbent layers are designed to hold blood, which means they need to be washed and dried with care.
In this article, you’ll learn exactly how to wash your period underwear, how often, what products to use, and how to care for them over time so they stay effective and comfortable.
What Is Period Underwear: Understanding Different Designs
Period underwear is engineered to do absorb menstrual blood and prevent leaks without shifting out of place.
Each pair is built with a layered system, including a top layer that wicks moisture away from the skin, one or more absorbent layers that hold blood, and a leak-proof layer that prevents it from seeping through. They’re integrated directly into the structure of the underwear to provide comfort and breathability throughout the day (or night).
There are two main designs used across brands:
1. All-in-One Absorbent Underwear
This is the most common style. The absorbent and protective layers are sewn into the fabric itself. You wear them, bleed into them, wash them. Everything is built in including the absorbent core, the moisture barrier, and the waterproof layer. These are ideal if you want a grab-and-go option that doesn’t require changing pads or carrying extras during the day.
2. Removable Pad Systems
Brands like THE KIT by Nookees use a modular system with a reusable base underwear and a detachable pad that clips or snaps into place. The absorbent part is removable, which means you can swap it out during the day without needing to change your entire pair of underwear. This is especially helpful on heavier flow days or when you’re traveling and need more flexibility.
Crucial First Step: Check the Care Label
Most period underwear brands include specific cleaning instructions on the care label. Always check the label sewn inside your underwear before washing. Follow the brand’s recommendations will keep your underwear in good condition and avoid damaging the absorbent or waterproof layers when washing with other clothes .
Before using period underwear for the first time, it’s important to wash and dry it. Washing helps open up the absorbent fibers in the fabric so they can do their job. If you skip this step, blood may stay on the surface instead of being absorbed, leading to leaks or discomfort. Starting with clean, fully dried underwear ensures the material is ready to absorb your flow effectively from the very first use.
The Golden Rule: Rinse It As Soon As You Can
When blood sits too long, it dries. That drying process hardens the fibers and creates the perfect environment for bacteria, stains, and odor to develop. It can also shorten the life of your undies, making them stiff and harder to fully clean later.
As soon as you change, rinse in cold water. Not warm (which can lock in stains), and not later (when you’re tired and forget). Take a moment, run them under cold water until it runs clear, and give them a gentle squeeze.
What Detergent Should You Use
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Clear, fragrance-free detergent: Fragrance-free detergents are less likely to irritate sensitive skin and won’t leave behind scents that can linger in the fabric.
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No dyes or essential oil blends: Detergents with dyes or essential oils can leave residues that may cause skin reaction and build up in the absorbent layers.
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Simple formulas that rinse clean: Simple detergents are easier to rinse out, which means there’s less chance of soap buildup that can interfere with absorption and cause odors.
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Eco or baby-safe brands: Eco and baby-safe detergents tend to be milder and free of harsh chemicals, protecting both the fabric and your skin without over-stripping the material.
Detergents To Avoid
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Softeners that leave a chemical film: Fabric softeners leave a residue on the material, which can block absorption and may cause irritation or unpleasant tastes if the underwear comes in contact with your skin.
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Enzymes that strip absorbency out of the gusset: Enzyme-based detergents can break down the specialized fibers in the gusset, reducing how much blood the underwear can hold and making it less effective over time.
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Bleach or whiteners that degrade the fabric: Bleach and whitening agents can weaken the fabric and break down waterproof or absorbent layers, shortening the life of your underwear and making leaks more likely.
How to Wash Period Underwear With Your Hands
Rinse with cold water.
Hold the gusset open and let cold water run through the core. Avoid hot water, as this can set the blood in the underwear, especially if you opt to hand wash . Cold water helps the blood release. Keep rinsing until the fabric feels softer.
Use mild, vulva-safe soap.
Work the soap in with the pads of your fingers. When it starts to foam, slow down. That lather needs to rinse all the way out.
Rinse until water runs clear and clean.
Rinse the underwear untill all the soap is rinsed out. You’re done when the water feels like water, not soapy, not cloudy, not faintly red. Check the seams & the gusset folds, as that is often where blood hides.
Press the water out.
Don’t twist it stretch the panties when rinsing. Just fold it between your palms and press. That protects the integrity of the gusset and keeps the fit.
Air Dry
You can hang the cleaned period undies on your washing line outside in the sun for a few hours to dry off.
How to Machine Wash Period Underwear
Rinse it first.
Before it ever touches the machine, rinse your underwear by hand under cold water. Let it run through until the water runs pale. This flushes most of the blood out and protects the rest of your laundry.
Use a delicates laundry bag, unless your brand says otherwise.
Mesh laundry bags protect against spin-cycle damage. But not every brand recommends them. If your care tag says no bag, then follow that. Otherwise, use one every time.
Choose the delicate cycle
Most period underwear needs cold water and a gentle cycle. That preserves absorbency and avoids blood setting. But not all styles are the same, so ensure to read your care label for specific instructions.
Use detergent that leaves nothing behind.
Use detergent that is fragrance-free, enzyme-free, and softener-free. If your detergent promises “brightening,” “whitening,” or “deep clean enzymes,” skip it. These agents cling to the fabric and block absorption, or they break it down over time.
Wash with darks or delicates only
If the underwear is fully rinsed, you can toss it in with your other darks or soft-cycle items. But avoid towels, or anything rough. Friction is one of the fastest ways to wear down layered gussets, especially at the seams.
Air Dry
Hang your period panties up outside on in an area with a draft indoors where it can dry off effectively. Only pack away or wear when it is completely dry.
What Temperature Should You Wash Period Underwear At?
Always wash in cold water - 30°C (85°F) or below.
Cold water is non-negotiable when it comes to period underwear. Blood contains proteins and iron. When exposed to warm or hot water, those proteins cook into the fabric, setting stains permanently and reducing absorbency over time. Hot water also breaks down elastic and waterproof layers faster, which shortens the lifespan of your underwear.
Can Period Underwear Be Tumble Dried?
Tumble drying period underwear will damage the very layers that make it effective. While it might be tempting to speed up drying time, the heat and friction of a tumble dryer break down the core structure of your period underwear , even on low heat.
Here’s what happens when you tumble dry them:
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The absorbent layers degrade. Heat weakens the fibers that hold fluid, making them less absorbent over time. What once held a full day’s flow might start leaking after just a few cycles.
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The waterproof barrier warps or melts. Many pairs have a leak-proof backing made from polyurethane laminate (PUL) or similar materials. In high heat, this barrier can wrinkle, crack, or lose its shape entirely, causing slow leaks you won’t notice until too late.
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Elastic stretches and seams weaken. The leg openings, waistband, and inner gusset seams rely on stretch fabric to stay fitted and prevent leaks. Heat exposure shortens their lifespan significantly, especially in multi-layered underwear.
Removing Odor From Period Panties
If you’ve worn your period underwear for a few cycles and they’re holding onto a metallic, or swampy scent, it means something’s built up that didn’t get washed out.
Smelly scent can be caused by dried blood that settled into the seams, or detergent that never fully rinsed. Either way, the fix starts with a soak, cold water only, and a splash of white vinegar. Let them sit for 20–30 minutes max, then rinse and wash like normal.
If the smell’s still there, it’s likely trapped between the absorbent layers. At that point, you can try an enzyme-based cleaner, as long as it’s bleach-free and made for delicates. Patch test first. And don’t soak overnight. Long soaks weaken stitching and can make the gusset stiff.
On-the-Go Period Care Instructions
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Rinse with Water When Possible: As soon as you can, rinse the gusset of your period underwear with plain cold water, whether from a sink, shower, or water bottle. Even without detergent, this helps prevent stains and odors until you can wash them properly.
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Use a Wet Bag: If rinsing isn’t possible right away, fold the used underwear inward (to protect the gusset) and store it in a breathable wet bag until you get home.
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Avoid Plastic Bags: Don’t use airtight or plastic bags, as they trap moisture and increase the risk of bacteria, mildew, and odor buildup.
Frequently Asked Questions
Yes, you can wash period underwear in the washing machine, as long as you follow the care instructions on the label. Before you machine wash, always rinse period underwear under cold running water until the water runs clear to help remove menstrual blood and prevent blood stains. Place your period undies in a laundry bag to protect the delicate fibers and absorbent layers. Use a cold cycle with a mild detergent and avoid fabric softener, bleach, or strong detergents that can damage absorbent materials. For best results, wash period underwear with other delicates or dark clothes, not with heavy or rough laundry. After washing, air dry by hanging on a washing line or drying rack.
To wash period blood out of underwear, start by rinsing the affected area under cold running water as soon as possible. Cold water helps lift blood stains without setting them into the fabric. Gently rub the gusset with your fingers or use a mild soap if needed. For tough stains, soak the underwear in cold water for several hours, then hand wash or machine wash with a gentle detergent. Avoid hot water and baking soda, as both can damage absorbent materials and delicate fibers. Always air dry period panties after washing, lay them flat or hang dry to preserve absorbency and comfort.
You don’t have to always wash period underwear separately, but there are a few important steps for proper care. Always rinse period underwear in cold water first to remove menstrual blood. If you machine wash, use a laundry bag and select a delicate cycle with a mild detergent. Wash with other delicates or dark clothes, but avoid washing with towels or heavy fabrics that can wear down the absorbent layer. Never use fabric softener, bleach, or strong detergents, as these can damage your period undies and reduce their ability to absorb menstrual blood. Keeping to these tips will help your period underwear last through many menstrual cycles.
You should avoid putting period underwear in the tumble dryer, especially on high heat, because high temperatures can damage the absorbent layer, waterproof barrier, and delicate fibers. This reduces your underwear’s ability to absorb menstrual blood and can cause shrinkage or warping. Instead, air dry your period panties by hanging them through a washing line dry, or laying them flat to dry completely. Air drying preserves the absorbent materials and extends the life of your favourite pair.
