Why your menstrual cup is leaking & how to prevent leaks


“Everyone’s body – and flow – is different, so it takes some trial and error to determine which period product is best for you.”

Menstrual cup leaks – oh no!

You’ve finally made the decision to leave tampons and pads behind in favor of an eco-friendly, clean, comfortable alternative. Congratulations! 

We’re guessing you’re here because those first few days of cup use have been a little, erm, messier than expected. Like, more-than-one-pair-of-stained-underwear messy. If that’s the case, don’t despair! Many days of menstrual cup bliss are still ahead: You may just need a little practice with insertion – or it’s possible that you need a different size. 

If you’re experiencing menstrual cup leaks (whether it’s with Flex Cup™ or a different brand), here’s what might be going on:

4 reasons your menstrual cup is leaking

1. Your menstrual cup isn’t inserted properly

A misplaced cup is by far the most common cause for menstrual cup leaking. Quite simply, menstrual cups take some getting used to. For women accustomed to tampons, their insertion practice is usually relegated to a haphazard one-finger shove up the vaginal canal; menstrual cup insertion, on the other hand, requires a bit more finesse and care, especially for novices.

In many cases, improper insertion occurs when the menstrual cup isn’t landing in the correct spot. This confusion can be alleviated with a simple anatomy lesson: the vaginal canal links the uterus to the vaginal opening, and the cervix is essentially a barrier between the uterus and vagina. During your period, blood flows through the cervix and into the vaginal canal. Your cervix is what ensures that your menstrual cup, disc, or any other period product of choice can’t get lost.

In an ideal placement scenario, your menstrual cup sits at least mid-way up the vaginal canal, just below the cervix, so that it can collect period blood with zero leaks. In order to get placement just right, make sure to relax your pelvic floor muscles before sliding your cup into your vagina – and try to push it back towards your tailbone rather than straight up like you would with a tampon. If your cup is too low in your vaginal canal, it won’t be as comfortable (and it’ll be more likely to leak). 

One of the simplest ways to prevent leakage and improve your cup experience is to simply get to know your body. Do some research on female reproductive anatomy, look at diagrams and pictures, watch YouTube videos – anything to help you visualize how your menstrual cup sits in the body, and by extension, why it’s leaking.

2. Your cup isn’t “popping” open

The “pop” is a descriptor for that magical moment when a menstrual cup finds that sweet spot beneath the cervix and flowers open. Visually, this process makes sense. Fold the cup so that it’s small enough to fit inside your vaginal walls, then let go and wait for the pop – when it does, you’ll have a complete seal with no gaps between the cup’s rim and your vaginal walls.

There are numerous ways to fold the cup, and they’re all perfectly valid: However, keep in mind that everyone’s vaginal muscle tone is unique, so certain folds may not work as well for you to create that perfect pop – and this may lead to those frustrating leaks. The only solution here is to just keep practicing and try a different fold. Here’s a quick breakdown of the pros and cons of three of the more popular folding methods:

  • The C fold: This is one of the simplest options. All it involves is folding your cup in half, forming the titular C shape (kind of like a taco). Many cup users find that the C fold allows the cup to pop open more easily than other folds.  Unlike other options, however, the C fold isn’t very economical when it comes to space: it’s fairly wide, which can make inserting it into the vagina a bit trickier for novices.
  • The punch-down (or tulip) fold: This essentially involves pushing down one side of the rim of the cup, then squeezing the sides together. Unlike the C fold, this option makes for a very narrow end-product, so insertion may feel much easier. The potential downside to this option is that it can be harder to pop open completely, due to how compact the folding process is.
  • The 7 fold: Insertion with the 7 Fold is similar to the Tulip/Punch-Down, but you may find that the cup opens up more easily inside your body. Fold your cup in half so that the lips touch. Then pull down the right side, forming a “7” shape with the lips of the cup.

Still not working?

If you’ve cycled through these options and read our troubleshooting guide but still haven’t found your perfect fold, you may need to do some manual adjusting.

One simple way to achieve that desired pop is to rotate the menstrual cup and wiggle it from left and right while tugging the base of the cup lightly downward. Once it’s properly inserted, you should be able to feel pressure from the suction when you try to pull it downward. You can also run your finger around the outside of the menstrual cup: If you feel a slight crease, it’s likely preventing the formation of a vacuum, so you’ll either need to put some pressure on your vaginal walls to help it open up or try taking it out and reinserting. 

3. You have a low cervix

Everyone’s vaginal anatomy is unique, so if the many tips and tricks you’ve played with aren’t solving your leakage problem, it’s possible that the natural position of your cervix has something to do with it.

Most cup instructions are written for women with high cervixes, but if yours lies low, you could encounter more of a learning curve with your cup (leading to unnecessary leaking). Cervix height and swelling can also change during the different stages of your menstrual cycle, so what works one day may not work the next.

The position of the cervix near ovulation (when you’re most fertile) vs. non-fertile stages of your cycle.

If you’ve never located your cervix before (or even if you’re just learning about cervix height for the first time), check out this guide courtesy of our resident Flexperts. 

If you have a low cervix, your menstrual cup may be too long, making it very easy to push the rim of the cup over to one side rather than creating a complete seal beneath the cervix. Alternatively, the cervix may end up sitting inside the cup. If you suspect this to be the problem, run your finger around the cup’s rim to see if you’ve missed the cervix, in which case you can try to pinch the base of the cup and pull down until it’s below the cervix. Then, angle the cup towards your cervix and do another finger check to ensure that everything is sitting properly.

What Else Does This Mean?

A low cervix also means you may need to empty your menstrual cup more frequently or consider a larger size, as your cervix could be dipping into the cup and taking away some of the space for blood to collect.

4. Your cup is the wrong size

For the most part, standard-sized menstrual cups provide ample room to collect all your menstrual fluid within a 12-hour period – the maximum amount of time you can safely wear your cup before emptying and cleaning it. For some women, however, a heavy flow means that a “standard” menstrual cup isn’t quite enough space for 12-hour wear

If you know you have a heavy flow and you’re experiencing frequent leaks, there are two possible solutions: First, try emptying your menstrual cup more frequently during your heavy days. This adjustment means that you may need to occasionally rinse your cup in a public restroom. If this sounds unappealing, or if you have such a heavy flow that this tip doesn’t do the trick, consider buying a higher-capacity cup. 

The average menstrual cup holds around 20 mL of blood, whereas larger sizes can hold anything from 30 to 42 mL – much greater than a tampon or pad’s capacity. If you’re trying to decide between the two Flex Cup sizes, here are the capacity stats: 

  • The Slim Fit Flex Cup holds 22mL and is 43mm in diameter
  • The Full Fit Flex Cup holds 30 mL and is 46mm in diameter

For most individuals, either cup size will work – it really comes down to choosing the best fit for your comfort and capacity needs. If you’re a first-time cup user or have a light to medium flow, we recommend the Slim Fit. The Slim Fit should work out for heavy flows, as well, you just may find that you have to empty it and reinsert a bit more frequently. If you have a flow that is on the heavier side or have had multiple vaginal births, try out the Full Fit Flex Cup. 

Wait – I’m still leaking!

If you’ve poked and prodded, wiggled and tugged, and tried every menstrual cup option on the market but leaks are still resulting in a messy period, it may be that the cup isn’t the best choice for your unique anatomy. 

So: you like the idea of an eco-friendly product that’s light on leaks but heavy on comfort, but the menstrual cup continues to let you down – and you don’t want to return to pads or tampons.

Enter the menstrual disc.

Unlike a menstrual cup, menstrual discs like the Flex Disc™ sit in the vaginal fornix – the widest part of the vaginal canal and even closer to the cervix. Menstrual cups use suction to stay in place, whereas discs work with your natural anatomy: They’re held in place by your pubic bone. Plus, with most discs, there’s no need to shop around for the proper size (Flex Disc is one size fits all).

The bottom line on menstrual cup leaks

Everyone’s body – and flow – is different, so it takes some trial and error to determine which product is best for you. Despite what your high school health class may have taught you, tampons and pads are far from the only options on the market. If you’re looking for an eco-friendly, user-friendly product that results in little to no leaking, we think Flex Cup is a great place to start. Ready to try something different? Test out the Disc, too (or get both in the Flex Discovery Kit). 

If you’re having trouble with Flex Disc or Flex Cup and none of the solutions in this guide are helping, have no fear! Reach out to our team by submitting a request or call us at (800) 931-0882.

This article is informational only and is not offered as medical advice, nor does it substitute for a consultation with your physician. If you have any gynecological/medical concerns or conditions, please consult your physician. 

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