Inserting a Flex Cup takes a bit of practice, but most people get comfortable with it within two or three cycles. The process comes down to three steps: fold the cup, slide it in at the right angle, and confirm it’s sealed. Here’s exactly how to do each part.
Clean the Cup First
If you just bought your Flex Cup, wash it with mild soap or a dedicated cup cleanser before your first use. Between periods, you can fully sanitize it by boiling it in water for 10 minutes on the stove. Keep it from touching the sides of the pot while it boils. Always wash your hands thoroughly with soap and water right before insertion.
The Flex Cup is made from 100% medical-grade silicone with no BPA, phthalates, or natural rubber latex. It’s hypoallergenic, so it’s a good option if you have sensitivities to other period product materials.
Fold the Cup Small Enough to Insert
A menstrual cup looks wide when it’s fully open, but folding it brings it down to roughly the width of a tampon. Two folds work well for the Flex Cup:
- C-fold: Press the sides of the rim together so the opening forms a narrow “C” or “U” shape. This is the simplest fold and a good starting point.
- Punch-down fold: Use one finger to push the rim down into the cup’s body, then squeeze the sides together. This creates a smaller, more tapered tip that some people find easier to insert.
Hold the fold firmly near the base so it doesn’t pop open before you’re ready. If the cup is slippery, rinsing it with cold water can help you grip it (and cold water also makes the silicone slightly firmer, which helps it hold its shape).
Find a Comfortable Position
Your body position matters more than you might expect. Sitting on the toilet, squatting low, or standing with one foot propped on the edge of the tub all work well. The goal is to relax your pelvic floor muscles, which makes the vaginal canal wider and the cup easier to guide in. If you’re tense, insertion will feel harder than it needs to be. Take a breath and let your muscles soften before you start.
Insert at the Right Angle
This is where most first-timers go wrong. The vaginal canal doesn’t point straight up. It angles back toward your tailbone. Aim the folded cup down and back, not straight up toward your belly button. Slide it in gently, pushing with your fingers until the entire cup, including the base, is inside the vaginal canal.
As you insert, pinch and twist the base of the cup. This helps the cup pop open inside you and begin forming a seal against the vaginal walls. You don’t need to push it as high as a tampon. The cup should sit low enough that you can reach the base and the pull-tab with your fingers, but high enough that it’s fully inside and comfortable.
Check That the Cup Has Sealed
A proper seal is what prevents leaks. Once the cup is in place, run a clean finger around the outside of the base. You’re feeling for any dents, folds, or pleats in the silicone. A fully open cup will feel round and smooth all the way around.
If you find an indentation or a section that hasn’t popped open, try one of these fixes:
- Twist the cup slightly by gripping and rotating the base.
- Press gently against the vaginal wall next to the dent to give the cup room to expand.
- Pull the cup down slightly and reinsert with a different fold.
You’ll know everything is right when you can stand up, walk around, and move without feeling the cup or noticing any leaking. A well-placed cup is virtually undetectable.
How Long You Can Wear It
Menstrual cups can be worn for up to 12 hours at a time. On heavier flow days, you may need to empty it more often, perhaps every 4 to 6 hours. On lighter days, the full 12 hours is realistic. Empty the cup by pinching the base to break the seal, pulling it out, rinsing it with water, and reinserting. The Flex Cup has a pull-tab that helps release the suction, making removal easier than with most other cups.
Why Leaks Happen and How to Fix Them
If your cup is leaking, the issue is almost always one of these problems:
The cup didn’t fully open. This is the most common cause. If there’s a fold or crease still in the silicone, there’s a gap where fluid can escape. Always do the finger check around the base after insertion.
It’s sitting too low. A cup that’s barely inside the vaginal canal won’t collect fluid properly. Push it a bit higher and recheck the seal.
It’s the wrong size. Flex Cup comes in two sizes. If a cup is too small for your body, it won’t create enough contact with the vaginal walls to hold suction. If it’s too large, it may not open fully. Choosing the right size based on your flow and anatomy makes a noticeable difference.
Your flow is heavier than the cup’s capacity. Even a perfectly sealed cup will overflow if it fills up. If you’re leaking after several hours on a heavy day, you just need to empty it more frequently.
Tips for Your First Few Times
Wear a backup liner or period underwear during your first cycle with the cup. This takes the pressure off while you’re still learning, and you won’t have to worry about a small leak ruining your clothes. Practice inserting and removing the cup in the shower if you want a low-stress environment to get the hang of it.
Some people find that a small amount of water-based lubricant on the rim of the cup makes insertion smoother, especially during lighter flow days when there’s less natural moisture. Avoid silicone-based lubricants, which can degrade silicone cups over time. Most people report that insertion becomes second nature after three or four uses, so give yourself a few tries before deciding whether the cup works for you.