A bell-shaped brand of menstrual cup (left) which is about 2 inches (5.7 cm) long, not including the stem. A disposable softcup (right) looks similar to a contraceptive diaphragm and is about 3 inches (7 cm) in diameter.
A menstrual cup is a flexible cup or barrier worn inside the vagina during menstruation to collect menstrual fluid. Unlike tampons and pads, the cup collects menstrual fluid rather than absorbing it. Menstrual cups are usually made from medical grade silicone.
Manufacturers have different recommendations for when to replace the cups, but in general they can be reused for years. Disposable menstrual cups are also available - these work in the same way as a regular menstrual cup except they are disposed of after every use or (for some brands) after every cycle.
An early version of a bell-shaped menstrual cup was patented in 1932, by the midwifery group of McGlasson and Perkins. Later menstrual cups were patented in 1935, 1937, and 1950. The Tassaway brand of menstrual cups was introduced in the 1960s, but it was not a commercial success. Early menstrual cups were made of rubber. Today, both silicone and rubber models are available. Most are reusable, though there is at least one brand of disposable menstrual cups currently manufactured.
In 1987, another latex rubber menstrual cup, The Keeper, was manufactured in the United States. This proved to be the first commercially viable menstrual cup and it is still in manufacture today. The first silicone menstrual cup was the UK-manufactured Mooncup. Most menstrual cups are now manufactured from medical silicone because of its durability and hypoallergenic properties. The German brand MeLuna is the only company to manufacture their cup out of TPE (thermoplastic elastomer). Menstrual cups are becoming more popular worldwide, with many different brands on the market, and there are different sizes and shapes available.
MeLuna Menstrual cups come in a wide variety of colors, stem styles, capacities and 'firmness' levels
There are two types of menstrual cups currently available:
The first type is a bell-shaped cup made of rubber (latex), silicone or thermoplastic elastomer (TPE). It is reusable and designed to last for up to 10 years. Some brands recommend replacement each year, as it is a hygiene product. Other brands recommend replacement after 5–10 years, stating that women have been comfortable using them up to 10 years. These bell-shaped silicone or rubber cups must be removed before penetrative vaginal sex.
The second type is made of polyethylene and resembles the shape of a contraceptive diaphragm. There are two types of polyethylene softcups: a disposable version designed for disposal after one use, and a reusable version, designed for re-use for one menstrual cycle. These polyethylene cups may be worn during intercourse, though they are not contraceptive devices.
Fleurcup small size (left) and large size (right). The stem may be trimmed.
Most brands have a smaller and a larger size. The smaller size is normally recommended for women under 30 who have not given birth vaginally. The larger size is normally recommended for women over 30 or who have given birth vaginally. The menstrual cups with the smallest size diameter are recommended for teenagers, as well as women who are more physically fit, as those with stronger pelvic floor muscles may find a larger cup uncomfortable. Length also needs to be considered: if a woman's cervix sits particularly low, she may want to use a shorter length cup. Capacity is important to women who have a heavier flow; however, all of the menstrual cups currently available have higher capacity than a regular tampon. A final consideration in selecting a menstrual cup is firmness/flexibility. Certain brands are firmer than others and one brand (MeLuna) offers three levels of firmness/softness. A firmer cup pops open more easily after insertion, but may be uncomfortable for some women.
Lunette "Selene" blue menstrual cup
Most menstrual cups come in colorless, translucent silicone. Several brands offer colored cups in addition to (or instead of) the colorless ones. Colored cups use a dye that is certified to be safe for food. (There is not a well-established method of certifying dye safety for medical devices, mostly because most medical device manufacturers are not interested in making colored products.) Translucent cups lose their initial appearance faster than colored - they tend to get yellowish stains with use. The shade of a colored cup may change over time, though stains are often not as obvious on colored cups. Stains on any color of cup can often be removed or at least lightened by soaking the cup in diluted hydrogen peroxide.
A menstrual cup correctly inserted low in the vagina
The menstrual cup is first folded, and then inserted into the vagina. It will normally unfold automatically and create a light seal against the vaginal walls. In some cases, the user may need to twist the cup or flex her vaginal muscles to ensure the cup is fully open. In most women, a menstrual cup will sit lower in the vagina than a tampon. If correctly inserted, the cup shouldn't leak or cause any discomfort, as with a tampon. Those who are familiar with inserting a non-applicator tampon should learn faster how to insert a cup, though there is still a learning curve. There are a number of different folding techniques that can be used for insertion. If lubrication is necessary for insertion, it should be water-based, as some lubricant ingredients can be damaging to the silicone. After up to 12 hours of use (less if the cup starts to overflow), the cup is removed by reaching up to the stem of the cup in order to find the base. Simply pulling on the stem is not recommended to remove the cup, as pulling it down will create suction. The base of the cup is pinched to release the seal, and the cup is removed. After emptying, the cup should be rinsed or wiped and reinserted. It can be washed with a mild soap, and sterilized in boiling water for a few minutes at the end of the cycle. Alternatively, sterilizing solutions (usually developed for baby bottles and breast pump equipment) may be used to soak the cup. 
Boiling a menstrual cup
Menstrual cups are safe when used as directed and no health risks related to their use have been found.
A 2011 randomized controlled trial in Canada measured urovaginal infection in a comparison of menstrual cup and tampon use, and found no significant difference in physician-diagnosed urovaginal symptoms between the 2 groups. The Journal of Women's Health has published a clinical study demonstrating the acceptability and safety of the Instead Softcup in both clinical and pre-clinical testing. Generally, menstrual cups do not significantly affect the population of vaginal flora, including the bacteria responsible for bacterial vaginosis (including yeast infections) or urinary tract infections. There have been no reported cases of toxic shock syndrome (TSS) occurring with the use of menstrual cups.
A large Fleurcup menstrual cup with capacity roughly 3 times greater than the absorbency of a Super tampon
A 2011 randomized trial in Canada investigated whether menstrual cups are a viable alternative to tampons and found that approximately 91% of women in the menstrual cup group said they would continue to use the cup and recommend it to others. In a 1995 clinical study involving 51 women, 23 of the participants (45%) found menstrual cups to be an acceptable way of managing menstrual flow. In clinical testing, after three cycles of softcup use, 37% of subjects rated the softcup as better than, 29% as worse than, and 34% as equal to pads or tampons. The 37% who preferred the softcup attributed their preference to "comfort, dryness, and less odor."
Most menstrual cups are made from medical grade silicone, which is a safe, easily cleaned, and hypoallergenic material. TPE has these same qualities and tends to be less expensive. The other material sometimes used for cups is latex, which is equally safe for people who are not allergic to it.
Reusable menstrual cups are more cost-efficient than disposable sanitary napkins and tampons, as they can be used for up to 10 years.
Since they are reusable, menstrual cups also help to reduce waste. Disposable sanitary napkins and plastic tampon applicators can remain in landfills for hundreds of years because they are not easily biodegradable.
Compared to other reusable feminine hygiene products (cloth menstrual pads, reusable tampon-style options like sea sponges, etc.) menstrual cups are easier to clean and sterilize after use and typically last longer.
Menstrual cups can be used when swimming or playing sports the way tampons can.
Many users, and some gynecologists, believe that menstrual cups are gentler on the vaginal environment than tampons. Tampons absorb all moisture in the vagina, including healthy fluids that are necessary to protect the vaginal walls and maintain the correct pH level and beneficial bacteria populations. Because they collect, rather than absorb menstrual fluid, menstrual cups affect the fluid balance of the vagina less than tampons. In addition, most mass-produced tampons contain rayon fibers, which can separate, stay in the vagina, and collect bacteria. The bleaching process many tampons undergo can also produce trace amounts of dioxin, a suspected carcinogen-although whether this causes health problems has not been firmly established. In any case, menstrual cup use is not associated with Toxic Shock Syndrome, an infection that can often be traced to improper tampon use.
Cups have a greater capacity than pads and tampons, and can be left in the vagina for up to 12 hours if not full, unlike pads and tampons which require more frequent changing. On moderate and light flow days, a woman need only insert the cup and clean and empty it at the end of the day rather than carrying several replacement pads or tampons. (Even when her flow is heavier, she will have to empty the cup more frequently but she need not carry disposable products.)
Because they keep menstrual fluid away from the vaginal walls and vulva and unexposed to air, menstrual cups have less odor associated with their use than pads and tampons.
When using a menstrual cup, the menstrual fluid is collected away from the cervix and held in liquid form as opposed to it being absorbed and held in semi-coagulated form against the cervix as is the case with tampons.
Since menstrual cups collect menstrual fluid inside the vagina and do not leak (if emptied often enough) the way tampons do, there is less break through bleeding and wetness during use than tampons or pads.
If a woman needs to note how much menstrual fluid she is expelling for medical reasons, a cup can allow her to tell more accurately. Some cups even have measuring marks on them.
Some women report that they bleed less or have shorter periods or fewer cramps when using a menstrual cup as opposed to tampons. While these claims have certainly not been clinically evaluated, there is reason to believe that some of the chemical components of tampons may draw more fluid out of the uterus than would come out naturally, and may encourage the uterus to contract, producing cramps.
Individual menstrual cups are more expensive than a package of sanitary napkins or tampons, so that, while within about six to twelve months using a menstrual cup saves women money (depending on the type of disposable products used previously and how frequently they were changed), it requires some upfront investment. A menstrual cup typically costs somewhere between US $25 and $40, though there are generic cups available for as little as $10.
Some women experience difficulty in inserting or removing the menstrual cup depending on previous experience and certain physical factors. Remedies for this include selecting a different size, shape, or material cup, using a water-based lubricant to ease insertion, changing the folding method for insertion, and practice.
Some women find menstrual cups uncomfortable initially. This may lessen with practice inserting the cup, selecting a more appropriately sized or shaped cup, and/or trimming the stem of the cup, if present.
Use of a menstrual cup can stretch or break the hymen, arguably even more than tampon use. Since some cultures value preservation of the hymen as evidence of virginity this can discourage young women in those cultures from using cups.
Women with pelvic organ prolapse may not be able to use menstrual cups (or tampons) comfortably or safely.
Menstrual Cup companies recommend that women using IUDs for contraception who are considering using menstrual cups should consult with their gynecologists before use. There have been rare cases in which women dislodged their IUDs when removing their menstrual cups; however this can also happen with tampon use.
^Stewart, Elizabeth B. The V Book: A Doctor's Guide to Complete Vulvovaginal Health. Bantam (2002), p. 96. ISBN 0-553-38114-8.
^Spechler S, Nieman LK, Premkumar A, Stratton P (2003). "The Keeper, a menstrual collection device, as a potential cause of endometriosis and adenomyosis". Gynecologic and Obstetric Investigation56 (1): 35–7. doi:10.1159/000072329. PMID12867766.