Home Cosmetic Science Talk Formulating Need Help Preserving a Natural Mouthwash

  • Need Help Preserving a Natural Mouthwash

    Posted by Alex777 on January 22, 2020 at 2:48 pm

    Thank you all in advance for reading/helping with this post!

    I am formulating a natural mouthwash. 

    Currently using Plantservative (Japanese Honeysuckle Extract) at 1% as a preservative. 

    The pH of the mouthwash is slightly alkaline. 

    I understand that natural preservatives don’t work well. Would it make more sense to run a challenge test first and if successful run a stability test after? 

    Is it possible to use thyme extract or essential oil to help with the preservation?

    How about using sodium hydroxide to get the pH to about 10? 

    We need a shelf life of about 18 months. 

    Just out of curiosity, it is more difficult to preserve a cream or a beverage/mouthwash?

    Thanks again in advance for reading and sharing your thoughts!

    Dr Catherine Pratt replied 4 years, 3 months ago 9 Members · 23 Replies
  • 23 Replies
  • EVchem

    January 22, 2020 at 7:30 pm

    Do you have alcohol in your mouthwash and how much

  • Pharma

    January 22, 2020 at 7:33 pm
    Is it a ready-to-use formula or a concentrate?
    A concentrate may be preserved with ethanol.
    I think that pH 10 is a bit too harsh for the mouth…
  • Alex777

    January 22, 2020 at 7:35 pm

    Hi EVchem,

    Thanks for responding to this post!

    There is currently no alcohol in the mouthwash. I want to avoid it because of the negative health effects it has. Alcohol also gives a strong bitter flavor and burning sensation to the mouthwash.

  • Alex777

    January 22, 2020 at 7:43 pm

    Hi Pharma,

    Thanks for responding to this post!

    The mouthwash is a ready to use formula. 

    I want to avoid alcohol because there are several studies that show it is detrimental to oral health. Also because of the stinging, burning and bitterness. 

    I agree with the pH of 10 being too harsh on the oral tissue. 

    There are a few companies that are mixing essential oils (cinnamon, thyme) with glycerin and are excluding preservatives. 

    However, they might not be providing full disclosures of their product labels.

    Listerine uses 21% alcohol, plus essential oils, plus sodium benzoate, so it is hard to believe that essential oils blended in with glycerin will actually preserve a product for 12+ months. 

  • Pharma

    January 22, 2020 at 9:28 pm
    Glycerol, sorbitol or xylitol may work at proper concentration by reducing water activity. As a rule of thumbs, 40% glycerol should be stable for years, 30% for several months. 20% ethanol is sufficient to stop bacteria from growing although it won’t kill them.
    Clover EO is a good antiseptic essential oil which also shows a local anaesthetic effect (taste/smell is unfortunately strong and less pleasant).
    Polyphenol-rich extracts (e.g. rathany root, rosemary) may be effective too and help against bleeding and sensitive gums.
  • Gunther

    January 22, 2020 at 10:43 pm

    1. Ethanol

    2. Methylparaben.
    Read ‘Evaluation of the ingestion of parabens during the use of dental caries products by healthy human volunteers’.

    Just don’t expect BS natural preservatives to work in such a demanding product.
    Not only sugars like sorbitol feed bacteria (unless the concentration is impractically high), but many people drink it using the bottle cap, so many mouth bacteria end up in the liquid.
    Mouthwashes are often used in the bathroom where there are lots of bacteria.
    And they are used for weeks or months after opening the bottle.

    Don’t ever sell a mouthwash without proper microbial challenge tests passed.

  • Alex777

    January 23, 2020 at 1:00 am

    Thank you Gunther and Pharma for your input. 

    Pharma, do you believe that a 20% glycerin concentration would have any preserving effects or would you need a minimum of 30% to see any preserving properties?

    Gunther, we do not want to incorporate parabens into our formulation. We want to go as natural as possible. 

    Thanks again!

  • EVchem

    January 23, 2020 at 2:26 pm

    Not to sound preachy, but I would say a marketing stance like ‘natural’ should be secondary to safety/quality of the product.  And there is so much misinformation about what ‘natural’ products are- parabens can be found in nature! The synthetic forms are identical and are produced in a controlled manner.

    I often wonder if the people who love the ‘natural’ positioning of products ever think about the sustainability of harvesting potentially rare or indigenous plants and the possible effects on the environment long term. Are natural extracts and oils tested as rigorously and consistently as synthetic products? My personal opinion is that is unlikely.

    If you’d like to read more on parabens or cosmetic safety:

  • Dr Catherine Pratt

    January 23, 2020 at 3:14 pm
    Use Leucidal 2% and Amp cide 2%
    hope this helps
  • Alex777

    January 23, 2020 at 3:27 pm

    Thank you EVchem and Dr. Catherine Pratt for your responses!

    Dr. Catherine Pratt, did you mean Leucidal and AMTicide Coconut? I believe the Amticide is for additional fungal protection, right? 

    Thanks again for your input!

    Seems like no one has faith in Plantservative (Japanese Honeysuckle)?

  • natzam44

    January 23, 2020 at 3:40 pm

    Plantservative is horrible. 

    I have tried it in four different formulas and every time they have lasted a grand total of 2-4 weeks. You may as well just keep your product in the fridge.

    Natural preservatives just don’t do the job well enough. I should also mention that if you want your product to be “natural” to use it as a marketing term, that you are probably better off just using synthetics. The market for “natural” mouthwash is very small and it isn’t a market which I would personally try to get into.

  • Alex777

    January 23, 2020 at 3:52 pm

    Hi natzam44,

    Thanks for your input. 

    At what concentrations did you use Plantservative?


  • Cafe33

    January 23, 2020 at 5:30 pm

    Hi Alex777, I am also developing a mouthwash but only for personal use. Here is a formulation from Handbook of Pharmaceutical Manufacturing, Volume 3, Liquid Products by Sarfaraz K. Niazi. 

    Qty/L (g)
    Menthol 10.00
    Eucalyptus Oil  10.00
    Cremophor RH 40 40.00
    Saccharin sodium 4.50
    Sodium citrate 2.00
    Citric acid 5.00
    Lutrol F 127 50.00
    Ethanol 96% 67.00
    Sicovit colorant QS
    Water 801.00

    Lutrol is a gelling agent. Notice that they only use around 6.5% Alcohol which is low compared to some of the formulations I have seen at 20% and more. I have not tried this formulation so I do not know what the mouthfeel is like but I certainly appreciate that it is a preserved with nothing more than low alcohol and pH.  

    I have also noticed many formulations which include synthetic and natural bisabolol which I found interesting, Hope this can help you. 

  • Alex777

    January 23, 2020 at 5:39 pm

    Hi Cafe33,

    Thank you so much for sharing that information!

    To be honest, it is hard to believe that a 6.5% ethanol concentration is enough to preserve a mouthwash. I thought 20% was the minimum?

  • Cafe33

    January 23, 2020 at 5:47 pm

    Maybe I spoke too soon about the Lutrol F 127? From my quick research it is only a rheology modifier. 

    Yes its only a small amount of Alcohol but the pH also seems to be very low. 

  • Alex777

    January 23, 2020 at 5:51 pm

    Thank you again for everyone who contributed to this post!

    I just have a few questions as I am understanding natural preservatives are not sufficient. 

    1. How much ethanol is required to preserve a product? Can you use under 20%? Under 15%?

    2. Will a combination of 10-15% glycerin and 10-15% alcohol have a synergistic effect in regards to preservation? 

    3. Is a pH of 10 sufficient enough to preserve a formulation?

    4. Below I have listed 3 separate, completely natural formulas. How are these products claiming to have a 2-year shelf life with no preservatives on their labels?!

    A. Purified, deionized, microfiltered water and ten parts per million of silver mineral (99.000% pure), calcium carbonate (natural chalk), sea salt, mustard seed powder, magnetic earth, active ionic minerals, essential oils of peppermint, eucalyptus, clove, wintergreen, and oregano.

    B. Deionized water, vegetable glycerine, extracts of echinacea angustofolia, echinacea purpurea, gotu kola, pure essential oils of peppermint, red thyme, cinnamon bark, eucalyptus globulus and lavender, plant saponins.

    C. Aloe barbadensis (inner leaf) juice, vegetable glycerin, cocos nucifera (coconut) oil, xylitol, mint (mentha piperita & spicata) leaf oil, mentha arvensis (menthol) crystals, ocimum sanctum (tulsi) leaf extract, azadirachta indica (neem) extract, calcium ascorbate (vitamin C), stevia rebaudiana (stevia) leaf/stem extract, sodium chloride (sea salt), activate (coconut) charcoal. 

    Hoping to hear from all of you!


  • Herbnerd

    January 23, 2020 at 6:58 pm

    Use Leucidal 2% and Amp cide 2%
    hope this helps

    @”Dr Catherine Pratt” Who supplies this in Aus?

  • natzam44

    January 24, 2020 at 12:19 am

    I used plantservative at 1% (maximum recommended by the supplier). When it didn’t work the first time, I increased it to 1.5% out of curiosity and though it faired slightly better, it was still terrible compared to all other preservatives I have used in the past.

    I have since tried it in two other formulas and have had similar results, with the best sample making it to 2 months before there was visible microbial growth.

  • Kimjiwon

    January 24, 2020 at 12:41 am

    Please visit my profile I have question about mouthwash :(

  • Alex777

    January 24, 2020 at 12:57 am

    @natzam44 Thank you for letting me know. I think as many of the previous users have mentioned, the best “natural” route would be ethanol. 

    I have experimented with 20% ethanol and it works well in the formula. Adds some mild burning but nothing close to Listerine. 

    Would you mind me asking what products you formulated that failed with Plantservative? I don’t need to know details jus curious if it was a cream based product or a liquid formulation.

    Thanks again! 

  • natzam44

    January 24, 2020 at 4:01 pm

    I tried plantservative in 3 products:
    - Basic hand lotion
    - Water-based hair pomade
    - Spray leave-in conditioner

  • Gunther

    January 27, 2020 at 5:34 pm

    Use Leucidal 2% and Amp cide 2%
    hope this helps

    Are they allowed in mouthwashes, or just for external, topical use?
    Especially because you’ll unavoidably swallow some of them.

  • Dr Catherine Pratt

    February 23, 2020 at 2:06 pm

    @Herbnerd you can get the natural preservatives from Trulux, New Directions just look around there are a few. You can use a much better Leucidal now on its own. I think it is called Leucidal SF or something like that. Just make sure it is broadspectrum and then you don’t need alcohol, especially if you want to go natural.

Log in to reply.