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Can your menstrual cup cause Toxic shock syndrome?

Recently a research paper on Toxic shock syndrome (TSS) and menstrual cup usage rocked our little cup universe and questioned our assumptions about correlation of TSS with menstrual cup usage. Let us take a detailed look at the study and other associated material about TSS before hitting the panic button.


The following study was published in American Society of Microbiology, May 2018. The abstract is as follows [1]:

Fifteen currently marketed intravaginal protection products (11 types of tampon and four menstrual cups) were tested by the modified tampon sac method to determine their effect on Staphylococcus aureus growth and toxic shock toxin 1 (TSST-1) production. Most tampons reduced S. aureus growth and TSST-1 production, with differences based on brand and composition, and S. aureus growth was higher in de-structured than in unaltered tampons. We observed higher S. aureus growth and toxin production in menstrual cups than in tampons, potentially due to the additional air introduced to the bag by cups, with differences based on cup composition and size.

Importance Menstrual toxic shock syndrome is a rare but severe disease. It occurs in healthy women vaginally colonized by Staphylococcus aureus producing toxic shock syndrome toxin 1 using intravaginal protection such as tampons or menstrual cups. Intravaginal protection induces TSS production by collecting catamenial products which act as a growth medium for S. aureus. Previous studies have evaluated the impact of tampon composition on S. aureus producing toxic shock syndrome toxin 1, but they are not recent and did not include menstrual cups. This study demonstrates that highly reproducible results for S. aureus growth and TSST-1 production can be obtained using a simple protocol that reproduces the physiological conditions of tampon and cup usage as closely as possible, providing recommendations for tampon or cup use to both manufacturers and consumers. Notably, our results do not show that menstrual cups are safer than tampons and suggest that they require similar precautions.

We reached out to one of the authors, for accessing the full paper. Unfortunately it was a paid article and we could not download the full research paper. However, we managed to have an email conversation with the author and could get a few important clarifications.

  • The study concludes through in-vitro standard method tests (not actual subject tests) that any insertable object such as tampon and menstrual cup in the vaginal environment can lead to multiplication of the Staphylococcus Aureus bacterium (S. Aureus) which can produce the toxin TSST-1. The toxin is found to cause Menstrual Toxic Shock among women.

  • The author clarified on the email that the conclusion of the paper has been mis-interpreted by the journalist who published it. The paper concludes that the TSS causing bacterium can grow in menstrual cup as well as tampons and similar precautions need to be adhered to by the user. What the paper claimed is *just* that - Menstrual cups are also associated with a risk of TSS and do not conclusively pose a risk higher than that of tampons.


Some known facts about TSS:

  1. Menstrual TSS is caused in the host by the reaction to the TSST-1 toxin generated by Staphylococcus Aureus (S. Aureas). Although nearly 20-30% humans are carriers to this bacterium, why menstrual TSS hits rarely (1 in a million) is not a well understood problem. The data is not enough as the condition is rare and reported cases are few worldwide.

  2. S Aureus can also cause Toxic shock among men and children. The route to infection is through cuts, burns and wounds. Symptoms include dizziness, vomiting, fever and rash and need immediate clinical intervention.

  3. Most of the menstrual toxic shock cases are among tampon users, but a few documented cases recently are associated with menstrual cup usage.

  4. Super absorbent tampon users were the first of the menstrual TSS victims. Two major reasons for increase in risk of TSS with tampons -

  • Tampons tend to absorb all liquid from the vagina walls, rendering them dry and more susceptible to micro tears and abrasions through which the toxin could enter the bloodstream. Also the fibres could remain stuck inside and be a medium for bacteria to keep growing even after the tampon has been taken out.

  • Long absorbency tampons meant that users could leave the tampon in for long hours [2], hence the chances of getting micro tears through vaginal dryness and multiplication of the toxin producing bacteria increase multifold.

  1. TSS is not a well understood condition by the medical community. Staphylococcus based TSS incidents in the United States are documented by Centre for Disease Control (CDC) website (Table 1 - Infrequently reported notifiable diseases) [3]. For instance, in the year 2014, only 59 cases of Staphylococcal TSS (not menstrual TSS) were reported in the United states. It is important to remember that menstrual TSS is rare even among tampon users.

Our takeaways from the paper and other discussions and studies surrounding TSS.

  • Conducting tests in a lab and what happens in a human body are two different things altogether. For instance, in-vitro tests cannot simulate micro-tears in the vagina of the user due to tampon usage or the self cleaning action of the vaginal membranes which keep the vagina healthy. In-vitro tests can only simulate the vaginal environment as a growth medium. So, in our opinion, the study was a theoretical exercise in establishing possibility of TSS for all insertable devices.

  • Silicone, as a material does not allow germs to grow on it easily. That's why silicone catheters are preferred to natural rubber ones. Silicone catheters are kept in human body upto 15 days at a time and are considered absolutely safe as a medical device. The same medical grade platinum cured silicone is being used for the cups. Considering that a cup is being removed and rinsed periodically, it is never in place for more than 7-8 hours at a stretch.

  • Study on actual subjects has shown that the cup material is inert and has no impact on the vaginal flora, which means there is no effect of cup on the pathogenic strain S. Aureus [4] present in the vaginal canals of the subjects.

  • TSS cases are so rare, that no one has any fool-proof data on it. This one documented case of TSS in Canada [5], could not prove that the cup was responsible. also, the patient in question had multiple complications (Hashimoto’s thyroiditis and chronic menorrhagia) before she used a cup.

Some precautions to be used with menstrual cup usage:

  • Do not leave in for long hours or days.

  • Do not share your menstrual cup with anyone else.

  • For peace of mind, perform sterilization by boiling after usage.

  • Observe proper hygiene of hands before and after inserting the cup.

  • Trim your fingernails and be careful not to scratch yourself while using the cup.

  • Do not try the cup when you are not on your periods. Period blood provides lubrication that would make abrasions unlikely. If needed, use a water based lubricant for insertion.

  • Do not use cup after childbirth, surgeries or infections associated with the vaginal canal. Allow for time to heal before resuming usage.

To cup or not to.. ?

In conclusion, we believe that every period product (for that matter any product!) has upsides and downsides of usage. Menstrual cups offer women the promise of economical, trash free and comfortable periods. By far, the benefits far outweigh the risks. By following proper hygiene practices, menstrual cup can be as safe (if not safer) as any other menstrual hygiene management product.

Referring to the study with adolescent girls in Africa [6], this was the conclusion: “Among this feasibility sample, no evidence emerged to indicate menstrual cups are hazardous or cause health harms among rural Kenyan schoolgirls, but large-scale trials and post-marketing surveillance should continue to evaluate cup safety."

So, can your menstrual cup cause TSS? Yes, it can, theoretically, but is much less likely than it scarily appears to be - With odds of one in a million, if you are a tampon user and perhaps, even less likely, if you use a cup.








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