for Better Menstrual Options

New Zealand's

One stop shop for alternative menstrual products

Kia Ora! Welcome to EnvironMenstruals.
Note from Anna-Maria: You may find that my recommendations conflict with those given by cup manufacturers. As a qualified and experienced microbiologist, I am rather concerned about the way manufacturers are misunderstanding and dismissing the concerns raised in recent research. The risk is not high, but it exists, and rinsing in hot water alone will do nothing to remove the biofilm build up. Sterilizing or scrubbing your cup every 8-12 hours, including boiling it for at least 60 seconds once a day will reduce the biofilm and therefore your risk of TSS or infection.
How you clean your cup is up to you. When you use a cup you are solely in control of its cleanliness and of your health.

How to clean a menstrual cup

Until very recently, the understanding around medical grade silicone and TPE was that it inhibited the growth of bacteria as the cells could not adhere to the material, so monthly sterilizing and twice daily rinsing was all that we thought was needed to get them clean. However, recent research has found that Staphylococcus aureus is able to form a thin layer on the surface after all. S. aureus cells are able to work together to hold onto surfaces that should otherwise be too smooth or electrically incompatible (think sticking things together with static electricity). This ‘biofilm’ is very similar to the one that forms on your teeth and causes plaque. This layer sticks so effectively, it can’t we removed by rinsing, even multiple times in hot water, so we now know that more thorough methods of cleaning are needed in order to prevent the build up of this bacteria.

Recommended cleaning methods:

The cup needs to be sterilized before use every time, not just the first day of use per cycle. Boiling is the most effective way of killing the biofilm. You can choose any method you like that suits you, steamer, microwaving, a pot on the stove, egg boiler machine, or even just boiling water poured over the cup in a mug. As long as the cup is fully covered in steam or boiling water for at least 1 minute, that will be sufficient to sterilize it against the bacteria and fungi that are likely to be growing on it. As long as you store it in a clean pouch, and don’t sneeze on it, or handle it too much in between, this should stay clean until you need it.
The idea situation is to have multiple cups so you can boil them after removal and always insert a boiled cup, but this isn’t always going to be possible for everyone, so here are some suggestions for the ‘in between’ cleans. These will reduce the biofilm enough to be safe, but you should still boil the cup at least once every 24 hours to ensure that it is completely killed:
  • The most effective method of biofilm removal (other than boiling) is scrubbing. Use an old toothbrush to scrub the surface of the cup, inside and out. Make sure to use an interdental brush in the holes and the stem (if it’s hollow). A fluoride toothpaste will aid this in a number of ways, but make sure to rinse well in clean water, or wash with a cup friendly soap, to remove the mint. This method, done thoroughly (with toothpaste), has been shown to reduce s. aureus biofilms by up to 99% (according to research on candida-staph biofilm removal - I’ll find the reference again if anyone is interested). Napisan, cup washes, sodium per-carbonate powder, salt, baking soda, and non-fluoride toothpastes could be used, but I don’t know how effective these and water only brushing are compared to using fluoride toothpaste. Incorporating a scrubbing component (even just rubbing with a cloth) will greatly increase the effectiveness of any other cleaning method you use.
  • Alcohol wipes (prep-pads, lunette wipes etc) or 70% isopropyl (aka rubbing) alcohol rubbed on with a cloth. These are easy to discretely carry in a purse or pocket. You need to use 70% alcohol for it to be effective. Lower concentrations would need to be in place for hours. Wipes with chlorohexidine are also appropriate. The rubbing action is important here, and helps break up the biofilm so the alcohol can get in and kill it. You can also spray alcohol or hydrogen peroxide on the cup then rub it off with a cloth. Make sure that you wait for any alcohol to dry completely, as this is how it kills the germs.
  • Soaking in a bacteriocidal solution - the advantage of most soaking methods is that you can reuse the solution multiple times: alcohol (a more dilute alcohol needs longer, 40% takes 4 hours), chlorohexidine mouthwash (10 minutes should be enough. May cause staining, definitely needs rinsing to remove any peppermint or spice), hydrogen peroxide solution (50/50 with water for 10 minutes is plenty, rinse with water. May fade coloured cups, will also remove staining), milton solution from tablet or liquid (mix according to package instructions. Soak for 10-15 minutes. You can make up a small amount, like 500ml, every few days and reuse it repeatedly). Milton solution breaks down into salt, water and oxygen over a day or 2, so the old solution is safe to pour down the drain or even into your garden. Peroxide and ethanol can be reused for months.
More research is needed into the effectiveness of various other cleaning methods. I hope to be able to give some clearer guidelines soon. These will still reduce the biofilm, but I don’t know by how much, so these should be used with caution until more information is available.
  • Cup wash. This should be used in conjunction with a brush as the scrubbing is necessary for breaking up the film. If you change your cup every few hours, rather than 8 hourly, this may be enough (more research is required - boil it daily, to be safe).
  • antibacterial soaps - these have mixed effectiveness against biofilms.
  • sex toy cleaners - chemically, these do look like they will do the job, but because biofilms are so hard to remove, I would add some scrubbing or rubbing with a cloth too, just to be sure.
Probably not safe or will damage the cup:
  • weak acids/bases, such as lemon juice, vinegar, citric acid, baking soda. These are probably too weak on their own.
  • essential oils of any kind, including thyme and tea tree. These are great for germs but they are not great for the cup material. Using thee will reduce the lifespan of the cup.
  • manuka honey. This would be excellent for killing the s. aureus biofilm, but it will encourage the candida, and you don’t want that.