Current evidence does not show that menstrual cups damage the pelvic floor. The only study that directly measured pelvic floor muscle function before and after menstrual cup use actually found modest improvements in muscle strength and endurance over three menstrual cycles. That said, the research base is thin, and the question is more nuanced than a flat “safe” or “unsafe” verdict can capture, especially for people with existing pelvic floor conditions, those who use an IUD, or those who experience pain during cup use.
What the Research Shows About Pelvic Floor Muscles
The concern that menstrual cups weaken or overstretch pelvic floor muscles is widespread online, but it does not have strong evidence behind it. The most direct study on this topic followed a group of healthy young women over three menstrual cycles of cup use and measured their pelvic floor muscle function at the start and end. Rather than finding damage, the researchers saw statistically significant improvements: stronger maximal voluntary contractions, more repetitions of sustained contractions, and a decrease in vaginal resting pressure, which can indicate reduced excess tension in the muscles.
1PubMed Central. The influence of the menstrual cup on female pelvic floor muscles variables: a prospective case seriesThis was a small preliminary study, not a large trial, so it would be a stretch to claim menstrual cups actively strengthen the pelvic floor. But it does push back against the idea that cup use causes weakening. The researchers suggested the improvements might come from the physical awareness required to insert, position, and remove the cup, which engages many of the same muscles targeted in pelvic floor exercises. Think of it less as a workout and more as repeated, mindful engagement of muscles you might not otherwise pay attention to.
A 2026 scoping review that pulled together all available research on menstrual cups and pelvic floor outcomes reached a measured conclusion: the evidence is too varied and too limited to establish that cups cause clinically meaningful pelvic floor dysfunction. Reported outcomes across studies included some pain-related symptoms and initial vaginal discomfort, but nothing pointing to lasting structural harm in healthy users.
2SpringerLink / Int Urogynecol J. Pelvic Floor-Related and Genitourinary Outcomes Associated with Menstrual Cup Use: A Scoping ReviewThe Suction Concern
One of the most persistent worries is that menstrual cups create a strong suction seal inside the vagina that pulls on pelvic organs or strains the muscles. Cups do rely on a seal to stay in place and prevent leaks, but the actual negative pressure involved is low. The seal forms against the vaginal walls and is easily broken by pinching the base of the cup or pressing a finger alongside the rim before removal.
The risk comes not from the seal itself but from how you remove the cup. Yanking a cup straight down without releasing the seal first creates a brief vacuum effect that tugs on the vaginal walls and, potentially, on nearby structures. Over many cycles, some pelvic health professionals have speculated this could contribute to downward pressure on the pelvic organs, particularly in someone who already has weakened support. But this remains speculative. The scoping review noted that the structural complications that have been reported were mainly isolated cases of reversible issues like temporary urinary obstruction, not progressive pelvic organ prolapse.
2SpringerLink / Int Urogynecol J. Pelvic Floor-Related and Genitourinary Outcomes Associated with Menstrual Cup Use: A Scoping ReviewThe practical takeaway: always break the seal before pulling. Pinch the base, slide a finger along the rim, or press the cup body inward to let air in. If you are routinely bearing down hard to push the cup within reach, that repeated straining could put more stress on your pelvic floor than the cup itself. A cup that sits too high or is difficult to reach may be the wrong size or shape for your anatomy.
When Pain Is Part of the Picture
Not everyone uses a menstrual cup painlessly, and pain during cup use appears to correlate with broader pelvic floor trouble. A cross-sectional survey of over 500 cup users found that women who experienced pain while using the cup scored worse on a pelvic floor dysfunction questionnaire. They also reported greater pain during insertion and removal, during menstruation in general, during intercourse, and higher levels of pelvic pain overall.
3Journal of Endometriosis and Pelvic Pain Disorders. The influence of pain presence on pelvic floor and sexual dysfunctions, and pain intensity-related variables in women using the menstrual cup: A cross-sectional surveyThe researchers noted that these differences, while statistically real, were clinically slight. And because this was a snapshot survey rather than a study tracking people over time, it cannot tell us whether the cup caused the pelvic floor problems or whether people who already had underlying pelvic floor tension were more likely to feel pain with a cup. That distinction matters. Pelvic floor muscles that are chronically tight or in spasm can make anything placed in the vaginal canal uncomfortable, from tampons to cups to speculum exams.
If you find cup use painful beyond a brief learning curve, that is worth investigating with a pelvic health professional rather than pushing through. Pain is a signal, not a hurdle to overcome with persistence. It may point to pelvic floor muscle tension, vulvodynia, or another condition that has nothing to do with the cup itself but that the cup makes more noticeable.
Cup Firmness and Sizing Are Not Standardized
One under-discussed factor in comfort and safety is how wildly menstrual cups vary in physical properties. A study comparing cups marketed to the same demographic, women under 30 who had never given birth, found that their total volume ranged from about 19 mL to 38 mL and the force needed to compress them by half varied from roughly 3.4 newtons to nearly 14 newtons. That is a fourfold difference in stiffness across products supposedly designed for the same user.
4PubMed Central. Comparison between menstrual cups: first step to categorization and improved safetyThe researchers also found no reliable correlation between a cup’s labeled size and its actual volume, or between its material and its firmness. In other words, you cannot look at a brand’s size chart and confidently predict how the cup will feel or perform. A “small” cup from one brand might be larger and stiffer than a “large” from another. The study concluded that without better transparency and regulation, consumers cannot easily estimate which cup suits them, and a poor choice could cause discomfort or injury.
4PubMed Central. Comparison between menstrual cups: first step to categorization and improved safetyThis has real implications for pelvic floor comfort. A cup that is too firm for your anatomy can press against the bladder or urethra, cause a persistent feeling of pressure, or make the pelvic floor muscles guard reflexively, which over time could contribute to muscle tension. A cup that is too soft might not open fully, leading you to repeatedly fidget with positioning and bear down. Neither scenario is dangerous for most people, but both can turn an otherwise neutral product into a source of chronic low-grade irritation.
Urinary Tract Issues and Rare Structural Complications
The vagina and the urinary tract are separated by a thin, flexible wall, and a menstrual cup sitting in the vaginal canal can press against the bladder or urethra. In most people, this causes nothing at all. In some, it can produce a feeling of urinary urgency or make it slightly harder to empty the bladder while the cup is in place. These sensations typically resolve immediately once the cup is removed.
In rare cases, the pressure becomes clinically significant. One documented case involved a patient whose bladder became partially entrapped by the menstrual cup due to the thinness and flexibility of the vaginal wall. The cup compressed the urethra and bladder neck, which, combined with a lower urinary tract infection, caused acute urinary retention. Symptoms resolved completely once the cup was removed.
5PubMed Central. Acute Urinary Retention and Menstrual Cup Use: Case ReportA large systematic review and meta-analysis looking at menstrual cup safety across many studies identified nine reports of urinary tract complaints among cup users, three of which involved temporary kidney swelling caused by urine backing up from ureteral obstruction. The same review also found five reports of severe pain or vaginal wounds and five cases of toxic shock syndrome.
6PubMed Central. Menstrual cup use, leakage, acceptability, safety, and availability: a systematic review and meta-analysisThese numbers need context. The review covered studies involving tens of thousands of cup users, and serious adverse events remained extremely rare. Another systematic review independently concluded that the menstrual cup appears to be a comfortable, safe, and efficient option for menstrual hygiene, noting only isolated cases of toxic shock syndrome, mechanical entrapment, and allergy across the literature.
7PubMed. Acceptability and safety of the menstrual cup: A systematic review of the literatureIf you notice that you suddenly cannot urinate, feel unusual pressure in your lower abdomen, or develop flank pain while using a menstrual cup, remove it. These symptoms are rare but should not be ignored.
Menstrual Cups and IUD Expulsion
If you use an intrauterine device, the question of menstrual cup safety takes on a specific dimension that goes beyond the pelvic floor: there is evidence that concurrent cup use may increase the risk of IUD expulsion. A U.S.-based survey of IUD users found that those who also used menstrual cups had roughly 2.75 times the odds of experiencing an IUD expulsion compared to non-cup users. No similar association was found with tampon or pad use.
8PubMed. Do menstrual cups increase risk of IUD expulsion? A survey of self-reported IUD and menstrual hygiene product use in the United StatesA systematic review examining seven publications on this topic found expulsion rates ranging from about 4% to nearly 19% across different studies, and the studies disagreed on whether the association was statistically significant.
9PubMed Central. Menstrual cup and risk of IUD expulsion – a systematic reviewThe mechanism most commonly proposed is that the cup’s seal, if it forms around or near the IUD strings, could displace the device during removal. It is also possible that bearing down to reach a high-sitting cup contributes. None of the studies can definitively prove the cup caused the expulsions, since IUD expulsion happens even without cup use, but the pattern is consistent enough that most reproductive health providers advise cup users with IUDs to break the seal carefully, avoid pulling on the IUD strings, and check string position regularly.
If your IUD strings were trimmed very short, the risk of accidental dislodgement during cup removal is likely lower, since there is less material for the cup rim to catch. But if you notice your strings feel longer or different, or if the cup seems to be sitting differently, check in with your provider.
People Who Should Be Extra Cautious
For the general population of menstruating people, menstrual cups appear safe for the pelvic floor based on available evidence. But certain groups may want to approach cup use with more thought or professional guidance:
- Pelvic organ prolapse: If you have been diagnosed with any degree of prolapse, the bearing-down involved in cup insertion and removal, plus the cup’s physical presence, could theoretically worsen symptoms. There is no strong research confirming this, but pelvic health physiotherapists often recommend discussing cup use with a specialist first.
- Hypertonic pelvic floor: If your pelvic floor muscles are chronically tight or in spasm, a cup may increase discomfort. The cross-sectional survey data showing worse pelvic floor scores among cup users with pain is relevant here, even though causality was not established.
- Recent pelvic surgery or childbirth: In the postpartum period or after gynecological surgery, pelvic tissues are healing and the pelvic floor is recovering. Most providers recommend waiting at least six weeks before inserting anything vaginally, and a cup that requires muscle engagement to position and remove may not be the best first choice during early recovery.
- IUD users: As discussed, there is a plausible and partially supported link between cup use and higher IUD expulsion risk. This does not mean you cannot use both, but it means being deliberate about seal-breaking technique and string checks.
How Menstrual Discs Differ
Menstrual discs are often lumped together with cups, but they work differently and may interact with the pelvic floor in distinct ways. A cup sits in the vaginal canal and relies on suction against the vaginal walls to stay in place. A disc sits higher, tucked behind the pubic bone in the vaginal fornix, and stays in place through anatomical positioning rather than suction.
Because discs do not create a seal in the same way, they avoid the suction-related concerns that dominate the cup conversation. There is no vacuum to break during removal, and less downward traction on vaginal walls. For someone worried about the bearing-down and seal-breaking involved in cup use, or for someone with a lower cervix where a cup tends to sit very low and press on surrounding structures, a disc may be a more comfortable alternative.
That said, the research on discs and pelvic floor outcomes is even thinner than the research on cups, which is already limited. The pelvic floor muscle study that found modest improvements was conducted specifically with bell-shaped menstrual cups, not discs.
1PubMed Central. The influence of the menstrual cup on female pelvic floor muscles variables: a prospective case seriesGetting the Fit Right
Much of the discomfort and many of the problems associated with menstrual cups come down to fit rather than to any inherent property of cups as a product category. Given the wide variation in cup dimensions and firmness that exists across brands, a poor fit can mean chronic pressure on the bladder, difficulty with removal that leads to straining, or a cup that shifts and causes irritation.
A few principles help. Cervix height matters: if your cervix sits low during menstruation (you can check by inserting a finger and noting how far in you reach it), you need a shorter cup, or the cup will press against the cervix and feel uncomfortable. If your cervix is high, a longer cup or one with a longer stem will be easier to reach without bearing down. Firmness should roughly match your muscle tone. Someone with a strong pelvic floor may find a very soft cup collapses before it opens fully, while someone with a naturally relaxed or recovering pelvic floor may find a firm cup creates unwanted pressure.
The lack of standardization across brands makes this trial-and-error more frustrating than it should be. Cup comparison charts maintained by user communities can help narrow options, but ultimately the only way to know how a cup interacts with your specific anatomy is to try it. If a cup consistently causes pressure, pain, difficulty urinating, or requires excessive bearing down to reach, switching to a different size, shape, or firmness level is worth the investment before concluding that cups are not for you.