Our underwear for periods absorbs your flow, blocks out odor, wicks moisture, and prevents leaks — so you feel fresh, dry, and comfortable! No pads, tampons, or other period products are needed. Our period-absorbing underwear is washable and reusable — providing a more sustainable alternative to single-use disposable products.

We recommend following the hip measurement to find the most accurate size. Be sure to measure your hips at their widest point, derrière included! We recommend sizing up in underwear styles that fit below the natural waist, or if you're looking for the best fit postpartum. The underwear should fit snugly but not so tight that it becomes uncomfortable.

We recommend starting with 3-5 pairs, so you’re covered for your entire period without having to do extra laundry. We offer Saver Sets and Custom Set discounts so you can build your collection and get more for less. Take our Know Your Flow quiz to find which underwear styles work best for your flow!

Thinx underwear is safe. Per- and polyfluoroalkyl substances, also known as PFAS, are absolutely not part of our product design and we do not treat our finished products with PFAS. We also take measures to help ensure these substances are not added to our products through material, design, production, facility, and supplier controls. We care deeply about the materials used in our products, putting comfort and safety at the core of our design, development and manufacturing.

Our sustainable period underwear is super easy to care for. Machine wash the undies with the rest of your laundry on a cold cycle before first wear and after each use. Steer clear of fabric softener and bleach. Hang dry to keep your undies at maximum performance. Do not iron.

We offer a 45-day trial on all orders, so if you’re unhappy with your purchase, we’ll try to make it right. Final sale items, Thinx “merch”, and gift cards are nonrefundable. Visit our online Returns Portal to begin a return or exchange.