A menstrual cup is a small, flexible, bell-shaped device that you insert into your vagina during your period to collect menstrual blood. Unlike tampons and pads, which absorb fluid, a cup catches and holds it. You remove it, empty the blood, rinse the cup, and reinsert it. Most cups can stay in for up to 12 hours at a time, and a single cup typically lasts several years, making it both cheaper and less wasteful than disposable products.
How a Menstrual Cup Works
You fold the cup and slide it into the vaginal canal, where it opens and forms a light seal against the vaginal walls. Blood flows into the cup rather than being absorbed into fibers the way it would with a tampon. This distinction matters: because the cup collects rather than absorbs, it doesn’t dry out vaginal tissue or alter the natural moisture balance inside your body.
When it’s time to empty, you pinch the base of the cup to release the seal, pull it out, pour the contents into the toilet or sink, and rinse it with water before reinserting. On lighter days, you may only need to do this twice a day (morning and night). On heavier days, you’ll likely empty it more often to prevent leaks.
What Cups Are Made Of
Most menstrual cups are made from one of two materials: medical-grade silicone or medical-grade thermoplastic elastomer (TPE). Both are the same class of materials used to make catheters and intravenous lines. They contain no latex, BPA, or heavy metals. Silicone cups tend to be slightly firmer, while TPE cups are often softer and more flexible. Neither material breaks down or releases chemicals during normal use.
Capacity Compared to Tampons
Menstrual cups hold roughly the same range of fluid as tampons and pads, around 20 to 50 milliliters depending on the size. A regular tampon holds about 20 mL of blood, while a heavy-absorbency tampon holds 31 to 34 mL. Cups follow a similar range: a small cup holds about 22 to 25 mL, and a larger size holds around 35 mL.
The practical difference is wear time. Tampons need to be changed every four to eight hours. A menstrual cup can safely stay in for up to 12 hours, because the blood simply sits in the cup rather than saturating an absorbent material. That longer window is one of the main reasons people switch, especially for overnight use or long workdays.
How to Choose the Right Size
Most brands offer two or three sizes, and the right fit depends on a few factors: your age, whether you’ve been pregnant or given birth, and the height of your cervix.
- Age and pregnancy history: Smaller cups are generally designed for people under 30 who haven’t had a full-term pregnancy. Larger sizes work better for people over 30 or those who have given birth vaginally, because pregnancy and delivery can change pelvic floor muscle tone.
- Cervix height: Your cervix sits at the top of your vaginal canal, and its position determines how high or low the cup will sit. To check, insert your longest finger into your vagina on or just before the first day of your period and feel for a smooth, slightly firm area with a small dimple in the center (similar to the tip of your nose). If you reach it at the first knuckle, your cervix is low and you’ll want a shorter cup. If your finger goes all the way in before you feel it, your cervix is high and a standard-length cup will work.
- Flow volume: If you regularly soak through heavy tampons quickly, a larger-capacity cup will give you more time between empties.
Some brands, like MeLuna, make shorter cups specifically for low cervixes in multiple sizes. Others, like Lena, offer a smaller, softer option for people with sensitive anatomy. Getting the size right matters: a cup that’s too small can be hard to reach for removal, and one that’s too large may feel uncomfortable or not seal properly.
Cleaning and Sterilization
During your period, a rinse with cold water between uses is the bare minimum, though rinsing with water and mild soap is better. Between cycles, you need a more thorough cleaning. The traditional advice is to boil the cup for several minutes, but research has found that you don’t actually need a rolling boil on the stove. Steeping the cup in freshly boiled water for at least five minutes (pour the boiling water into a mug, drop the cup in, and cover it with a plate) is effective at removing harmful bacteria, including the type responsible for toxic shock syndrome. Washing with soap before steeping adds an extra layer of cleanliness.
Safety and Toxic Shock Syndrome
Toxic shock syndrome (TSS) is the risk most people worry about. The overall picture is reassuring but worth understanding in detail. A large meta-analysis reviewed 43 studies covering over 3,300 menstrual cup users and found only five reported cases of TSS associated with cup use. A separate study of 751 schoolgirls using menstrual cups in Kenya reported zero TSS cases.
That said, laboratory research has found that cups may actually allow slightly higher growth of the bacteria behind TSS compared to tampons, likely because the cup introduces a small pocket of air into the vaginal canal. In practice, the risk remains very low. Following the 12-hour maximum wear time, washing your hands before insertion and removal, and sterilizing between cycles all reduce it further.
IUD Users: A Specific Risk
If you have an intrauterine device (IUD), menstrual cups deserve extra caution. A case-control study found that cup use was independently associated with about three times the risk of IUD displacement compared to non-cup users. The IUD expulsion rate was 5.9% among cup users versus 0.5% among non-users. The likely cause is the suction created when you remove the cup, which can tug on IUD strings or shift the device itself. If you use both, breaking the seal by pinching the cup base before pulling is essential, and trimming IUD strings shorter with your clinician’s help may reduce the risk.
Cost Over Time
A menstrual cup typically costs between $20 and $40 and lasts anywhere from two to ten years depending on the material and how well you care for it. Over time, that works out to roughly 5% of the cost of pads and 7% of the cost of tampons. For someone spending $5 to $10 a month on disposable products, a single cup pays for itself within a few months and saves hundreds of dollars over its lifespan. The environmental savings are significant too: one cup replaces thousands of single-use tampons and pads that would otherwise end up in landfills.
The Learning Curve
Most people need a few cycles to get comfortable with insertion and removal. The fold-and-insert technique feels unfamiliar at first, and getting the cup to open fully and form a proper seal takes practice. Running a finger around the base of the cup after insertion helps confirm it’s fully open. If you feel pressure or notice leaking, the cup likely hasn’t sealed correctly, and repositioning it or trying a different fold usually fixes the problem. Wearing a panty liner as backup during your first few cycles can take the pressure off while you figure it out.
Removal can feel awkward initially too, especially with a higher cervix. Bearing down with your pelvic muscles pushes the cup lower, making it easier to reach. Pinching the base before pulling breaks the seal and prevents the uncomfortable tugging sensation that catches first-time users off guard.