I just wanted to share something with everyone, and I hope it helps. Like many people here, I’ve been REALLY curious about gathering some facts on proper care of medical grade silicone. So I decided to turn to someone who works with this material regularly-- and ask them their professional opinion. I have forwarded the below letter to the head of a custom medical grade silicone molding company (they take custom moldings from hospitals for patients, and create artificial body parts of various kinds), and he sent me his reply.

Here is the company I contacted:


Here is the letter I wrote:

Dear Richard,

I was wondering if you could help me. I have a question about medical grade silicone-- Are there any sterilizing/cleaning solutions or lubricants that can damage it? I ask because I’m part of an online support community of people who use “menstrual cups”-- small, flexible cups made of medical grade silicone, that are worn internally, to collect menstrual fluid, rather than absorbing it. The manufacturers recommend that during use, we should wash them daily with mild, perfume-free soap. Then sterilize by boiling for 5 minutes. Some of the companies forbid most sterilizing solutions, claiming they damage the silicone. But many of us aren’t sure what to believe on this matter. Especially when it comes to things like rubbing alcohol, peroxide, oil-based lubricants, etc. We wonder if the company’s recommendations are meant to increase sales of their special “cup wash” or to make our cups discolor faster, so we buy new ones more often. Could you (or someone you are associated with) please help to shed some light on this subject?

Thank you in advance-- Melissa

And here is what he had to say:

Dear Melissa,

My background consists of 30 years as a Research and Development Engineer involved in the development of silicone elastomers and implantable silicone devices. I agree with the manufacturers recommendations for cleaning the silicone cups. Silicone has poor resistance to acids and bases found in sterilizing solutions and hydrogen peroxide. I have personal knowledge of silicone degradation caused by beta dyne solutions commonly used as a micro biocide in surgery. Isopropyl alcohol (IPA) can cause slight temporary swelling of the silicone, but as long as it is allowed to evaporate completely it will not deteriorate silicone. Oil based lubricants can swell/permeate the silicone and may not readily evaporate and can cause a loss in physical properties. My main concern with oil based lubricants would be biocompatibility in such a sensitive tissue environment.

Best Regards,
Richard Dumas
Director of Technical Service
Applied Silicone Corporation
270 Quail Court, Santa Paula, CA 93060 USA
Email Address: (removed for his online privacy, send me a private message, if you feel you need to speak to him)

Naoko Kensakumistressnaoko on April 13th, 2009 04:22 am (UTC)
So that means cleaning with hydrogen peroxide isn't recommended, right?
melissa569melissa569 on April 13th, 2009 04:27 am (UTC)
Pretty much, yeah. But rubbing alcohol is ok, just give it time to evaporate. And luckily, its just as easy to get as peroxide, so I'd say its a pretty simple switch. But of course, rinse VERY well afterward.
(no subject) - mistressnaoko on April 13th, 2009 04:32 am (UTC) (Expand)
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(no subject) - mistressnaoko on April 13th, 2009 04:38 am (UTC) (Expand)
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(no subject) - mangojellytoast on April 13th, 2009 08:40 pm (UTC) (Expand)
(no subject) - melissa569 on April 18th, 2009 12:35 pm (UTC) (Expand)
(no subject) - mistressnaoko on April 18th, 2009 02:46 pm (UTC) (Expand)
melissa569melissa569 on April 13th, 2009 04:26 am (UTC)
So in short, rubbing alcohol IS safe to sterilize with, as long as you allow it plenty of time to evaportae. Which comes as a BIG relief to those of us who may find boiling a bit of a hassle, or too time cosuming (or if mixing kitchen and bathroom products is a taboo in your culture/family). Also good news for women traveling, or living in dorms. And I must admit that even I myself am a bit relieved.
KaleidoscopeEydkaleidoscopeeyd on April 9th, 2014 04:22 pm (UTC)
Thanks so much for this! I've been wanting to use alcohol "prep pads" or "wipes" but I wasn't sure if it would make the cup dry or crack. Excellentt o hear from a professional in the medical industry.
Katzhukora1 on April 13th, 2009 04:46 am (UTC)
Wow, nice leg work tracking this down! I generally stick to boiling and soap meself, but since my Lunette is starting to show a little discoloration I was starting to think about roving through the tags for other "deep" cleaning options. Guess now I know what's what. ;)
tethyss on April 13th, 2009 04:48 am (UTC)
That is some terrific information. I've been wondering about the hydrogen peroxide; it's what I've been using for 9 cycles and have been thinking I felt a change in my cup, as if it's gotten a little sticky and isn't quite as soft.

You got me thinking though. What's a menstrual cup like? Baby bottle nipples. There are microwave steam sterilizers for them (truly sanitizers, but sterilize is the common verbalism). Would they perhaps be an excellent way to clean our cups? There are also steam bags which could be handy for discreet use in a crowded living situation.

I did come across this article which states that yeast is even killed off after only 15 seconds and had some other interesting info on the subject of microwave sterilization.
aedificaaedifica on April 13th, 2009 03:56 pm (UTC)
I think baby bottle nipples are usually rubber rather than silicone, though, aren't they? (I haven't seen one in a long time, but that's what I remember them being.)
(no subject) - tethyss on April 13th, 2009 09:55 pm (UTC) (Expand)
(no subject) - aedifica on April 13th, 2009 11:02 pm (UTC) (Expand)
(no subject) - thatgirljj on April 14th, 2009 05:44 am (UTC) (Expand)
Jackieagraciado on April 13th, 2009 05:00 am (UTC)
this was very awesome of you to do <3
Kitkitrinlu on April 13th, 2009 05:03 am (UTC)
That's great to know, thanks for this :)
newselenenewselene on April 13th, 2009 10:14 am (UTC)
Thanks for the info. I have been wondering about cleaning solutions.
It has also been said that peroxide would just discolor/bleach stains and not remove the actual stain material; that actually happened to a tiny spot I got on the rim of my Divacup.
stweasley84: stephysnapelovestweasley84 on April 13th, 2009 11:50 am (UTC)
I know your letter asked about oil-based lubricants...what about water-based lubricants? Nine times out of ten, when I have to put my cup in during the morning, I need to use lubricant. Would water-based lubricant also harm the cup?

I don't want to break-down my cup any faster. Nor do I want any sort of crazy reaction going on between my cup, lube, and my lady bits.
melissa569melissa569 on April 13th, 2009 12:33 pm (UTC)
Cup manufacturers say that water-based lubes are fine. But make sure they don't contain glycerin because its a sugar, and sugars can cause/agrivate yeast infections (on a very personal note-- be sure to tell the same to any lover who suggests sweets in the bedroom, lol).
D: lol irlmangojellytoast on April 13th, 2009 08:41 pm (UTC)
this is awesome! Thanks for posting it.

"biocompatibility in such a sensitive tissue environment. "

Hahahaha. Well phrased, Richard Dumas.
kagentrayevyn on April 13th, 2009 10:03 pm (UTC)
that made my day too.
every breath is a needle to my heartjemm on April 13th, 2009 09:40 pm (UTC)
Okay, he mentions acids, I'm wondering if vinegar would be a no go then? I boil mine with a splash of vinegar and it comes out all sparkly clean.

I wonder how taken aback he'd be if he started to receive tons of e-mails on this subject, hahaha.
melissa569melissa569 on April 13th, 2009 11:22 pm (UTC)
He'd probably hate me, hahaha. But yeah, I was wondering the same thing myself... It might be safe to assume that. I know that in candida/yeast cleansing diets (on the back of yeast cleanse tablet bottles), they tell you to avoid "acid" foods. And on the list is citrus, tomato, and vinegar... So maybe.
(no subject) - jemm on April 15th, 2009 10:46 pm (UTC) (Expand)
(no subject) - theinfamousj on December 11th, 2010 11:34 am (UTC) (Expand)
iudmamaiudmama on April 15th, 2009 04:24 pm (UTC)
I'm kind of surprised to see that he says silicone and hydrogen peroxide are a poor combo based on http://www.ozoneservices.com/articles/004.htm, Material Compatibility with Hydrogen Peroxide (H2O2) from http://community.livejournal.com/menstrual_cups/1388177.html last fall...
It says the compatibility for hydrogen peroxide and silicone is "excellent" for 10% solution and "good" for all others.
melissa569melissa569 on April 18th, 2009 12:42 pm (UTC)
He was most likely basing it on what he's seen in his experiences, rather than the mathematical/scientific equasions. I don't know, I feel like I would trust what time has shown, rather than numbers. Plus its seems like it would be faster to swab with alcohol, let dry, and rinse (for sanitizing purposes) than it would to dilute peroxide and soak it for prolonged periods of time.

But if I was going to attempt peroxide (say for the purpose of removing stains?) I would play it safe and seriously delite it to reduce the risk, as you suggested.
indigomoonindigomoon on May 8th, 2009 09:19 pm (UTC)
Hydrogen Peroxide
I have been soaking my diva cup in hydrogen peroxide after each period to remove staining in the holes. A couple times I've even left it soaking for a month and I've never had problems.
mpbowers on September 3rd, 2009 12:26 am (UTC)
I know this is an old post. I noticed you were worried about rubbing alcohol residue still being on the cup. Alcohol evaporates completely so there won't be any residue.
ergomocah on September 16th, 2009 07:28 am (UTC)
Grapefruit Seed Extract?
Great info here! I'm going travelling to India where I'll be staying in an ashram with no access to hot water and was looking for a way to clean my diva cup without having to boil. Rubbing alcohol seems like a fairly safe option, but in the interests of not having one more thing to take with me I thought I'd see if anyone has tried using Grapefruit Seed Extract for sterilizing at the end of the cycle? Anyone know if that could damage the silicone & / or have any harmful effects internally?

ジャねこ]: Chemisttheinfamousj on December 11th, 2010 12:25 pm (UTC)
He does have a way with words, doesn't he. His most convoluted sentence is, of course, the one we all want information from.

"Silicone has poor resistance to acids and bases found in sterilizing solutions and hydrogen peroxide. I have personal knowledge of silicone degradation caused by beta dyne solutions commonly used as a micro biocide in surgery."


"Silicone has poor resistance to acids and bases found in sterilizing solutions ... I have personal knowledge of silicone degradation caused by beta dyne solutions commonly used as a micro biocide in surgery."

Aside from the fact that it is Betadine (brand name for an iodine solution) that has a wide range of pHs (pH: 1.5-6.5; source MSDS, all of them in the "acid" side of the spectrum, I think it is important to understand that Betdine, and for that matter all halogens, is known to have poor interaction with silicone (source: Plast Reconstr Surg. 2000 Dec;106(7):1665. The effect of betadine on silicone
implants. Becker H, Becker CD.
). This doesn't really mean that acids affect around silicone. And certainly doesn't provide any infromation about bases. Instead, it seems to back up chemical knowledge that halogens, of which Betadine is one, should not be reacted with silicone. And certainly backs up the scientific article used as the source.

As for acids, a quick PubMed journal search will show that silicone is the container of choice for a large number of acids that range in pH to those that are more corrosive than vinegar - itself a 3 percent solution of acetic acid. (just one of many sources: The Effect of 2-M Hydrochloric Acid on Silicone Rubber Central Venous Catheters) So while there have been no studies specifically on acetic acid's effect on silicone, I'd imagine that it is one of non-reactivity since something that is more corrosive was nonreactive. In other words, vinegar will not react with your cup.

There is one acid that will react with silicone: Hydrofluoric acid. It is a halogen, which we have already covered above. And furthermore, if you have access to HF, you are already educated/trained in how to use it and likely wouldn't even think to use it as a sterilizing solution. As the kiddos say, "That shiz is nasty."

Now we shall move on to bases. Bases and silicone are a no no. But you don't have access to any household bases, other than Draino/Liquid Plumber/Lye and you already know better than to try to disinfect in that, right?

So in conclusion, his only personal experience was with Betadine and he extrapolated to acids and bases. Betadine is a halogen. Halogens and bases should not be mixed with silicone. Acids are just fine. Acids of any type (minus the one acid that is a halogen). Use your vinegar with abandon.

"Silicone has poor resistance to acids and bases found in sterilizing solutions and hydrogen peroxide."

I would now like to draw attention to the fact that by reading this, you may think that

a) acids and bases are found in hydrogen peroxide
b) hydrogen peroxide is an acid
c) hydrogen peroxide is a base

ジャねこ]theinfamousj on December 11th, 2010 12:26 pm (UTC)
All three are false. Hydrogen peroxide is a peroxide. Peroxides are rather nasty chemicals as chemicals go. And fickle. They lose potency rather quickly. They decompose into harmless water and harmless oxygen gas in the presence of sunlight or cells. As in human cells. Or bacterial cells. I generally steer as clear as possible of peroxides when it comes to my personal cells, but according to Effect of saline exposure on the surface and bulk properties of medical grade silicone elastomers which purposefully subjected medical grade silicone to differing concentrations of saline as well as hydrogen peroxide, "Tensile strength, elongation at break, and the elastomer stress measured at 100% or 200% elongation did not change significantly for peroxide..." (you can read the entire abstract if you want, just click the title.)

Hope this helped.