Menstruation may sometimes fill us with dread, but using the right period products can take environmental anxiety out of the equation.

We have more menstrual products to choose from than any of our foremothers, but from an environmental perspective, one option leaves all others in the dust.

“Menstrual cups are a really clear winner,” said Pippa Notten, a sustainability consultant who analyzed the environmental impact of menstrual products for the United Nations Environmental Program.

Menstrual cups are a fraction of the cost of single-use products, can be changed as little as twice a day and minimize your exposure to unwelcome additives.

However, certain conditions, including vaginismus and extremely heavy flow, can make menstrual cups a nonstarter. But don’t despair! Other options — including reusable pads, period underwear and reusable tampon applicators — can still “meaningfully and significantly” reduce the environmental impact of your cycle, said Notten, who holds a doctorate in chemical engineering.

The Holy Grail of period products

Menstrual cups are bell-shaped products, usually made of silicone, inserted into the vagina to catch, rather than absorb, blood. They last up to 10 years if cared for properly, but you don’t have to use one for a full decade for it to be worth it, Notten said.

Research indicates menstrual cups “break even” environmentally, meaning they’ve saved more energy and resources than it took to produce them, within the first couple cycles of use. So, it’s fine to try out a few menstrual cups to find your Goldilocks fit.

Across their lifetime, menstrual cups represent a tiny fraction of the energy and resources that go into single-use products. They require no bleaching or chemical additives for absorbency and don’t pile up in landfills or litter beaches.

Other reusables: Pads and panties

If you can’t use menstrual cups for medical or cultural reasons, the next best options are reusable pads (cloth inserts you fasten to your underwear and change several times a day) and period underwear (which uses super-absorbent synthetic materials to handle eight to 12 hours of flow).

Experts emphasize that washing period panties and pads incorrectly can “eat up” the environmental savings. That’s because washing in hot water takes a surprising amount of energy. Instead, rinse in cold water and then wash cold.

But which is better environmentally, period underwear or reusable pads? Most analyses indicate they’re very similar, occasionally giving period underwear a slight edge because it’s also functioning as, well, underwear.

Period panties have longer wear times but shorter lifetimes than reusable pads.

To achieve those longer wear times, up to 12 hours, many brands of period undies use super-absorbent synthetic materials, often polyester and nylon, which are plastic-based fabrics made from petroleum.

In 2023, a class-action lawsuit made waves when test results found PFAS, the so-called forever chemicals that can have negative impacts on human health, in Thinx menstrual underwear, which were marketed as “organic” and “natural.” (Thinx denied wrongdoing as part of an eventual settlement and emphasized that the agreement was not an admission of guilt.)

Scientists aren’t certain if and how much PFAS are absorbed through mucosal membranes like the lining of the vagina. Test results on period undies since then have been varied, and PFAS have also been found in reusable pads, single-use pads and tampons.

To avoid PFAS, your best bet is, once again, the menstrual cup.

In case of emergency: Single-use products

What if you’re in a pickle: Your period starts unexpectedly and you have to buy single use?

First, wastewater treatment experts implore you to remember these products are not flushable. That can block pipes and cause raw sewage to back up into homes and the environment.

But the main environmental impact of single-use products isn’t where they end up. It’s how they’re produced.

Susan Powers, a professor of environmental engineering at Clarkson University in Potsdam, New York, said she “dissected” single-use pads and tampons to try to reverse-engineer what goes into each. (Because menstrual products are legally considered medical devices in the United States, manufacturers don’t have to disclose the ingredients.)

According to Powers’ research and other analyses, there’s not a clear winner between single-use pads and tampons. Looking at a range of factors — including land and water use, chemical pollution from the factories that produce synthetic absorbents and contribution to climate change — tampons score better in some categories while pads pull ahead in others.

One way to mitigate a single-use tampon’s environmental impact is to opt for tampons without applicators, which are responsible for a significant share of the environmental effects. Switching to a reusable applicator paired with “loose” tampons is probably the easiest swap you can make today, without any adjustment phase.

As long as they’re washed properly, any of the reusable period products score better than single-use. That’s because, when it comes to single-use products, “it’s not the way you use them or the disposal that happens downstream,” Powers said. “It’s the fact that we’re making things to use for hours and then throwing them out.”