Does chamomile have the same potential to cause methemoglobinemia as benzocaine/orajel?

On the 21st of November 2013 Vashra asked me about the potential of chamomile to cause methemoglobinaemia, apparently the same effect produced by benzocaine/orajel. Well, I always love to help, but my free time is nearly null, and now with a child making me change nappies and feed him every 2 to 3 hours, is ever more complicated. Nevertheless, I want to maintain the blog as active as possible and I am now using a few moments of my paternity leave to read a little more about what is bugging my readers' brains. For starters, let me assume my ignorance and state that there are a lot of things here I am not familiar with, thus I decided to learn about them to make a little sense before thinking of researching adequate answers. 

Methemoglobinaemia - "is a blood disorder in which an abnormal amount of methemoglobin -- a form of hemoglobin-- is produced. Hemoglobin is the molecule in red blood cells that distributes oxygen to the body. Methemoglobin cannot release oxygen. In methemoglobinemia, the hemoglobin is unable to release oxygen effectively to body tissues." [1]

Benzocaine -  "Benzocaine is a local anesthetic (numbing medication). It works by blocking nerve signals in your body. " [2]

Orajel - a pharmaceutical used in adult and child oral care to counteract pain generated by infection and/or teething. [3]

So basically what Vashra wants to ask is if chamomile can cause a blood disorder in which an abnormal amount of methemoglobin is incapable of adequate releasing of oxygen into body tissues, apparently an effect previously observed as result of using Benzocaine. Benzocaine being the active substance of the pharmaceutical Orajel used, for the sake of the example, in calming teething pain in children.

By searching the web I came across a page referring the Food and Drugs Administration website, where one can find the immediate awareness alarm to several gels and liquids containing benzocaine and the observed cases of teething children poisoned by this substance. It occurs that benzocaine reduces the oxygen available in the blood stream and symptoms can  appear at any time point [4]. There is a special danger with over-the-counter products containing benzocaine as they are readily available, therefore it is quite important to reassure parents that there are different options on the market that can help relieve pain in children and toddlers.

Hot and cold gel packs mold themselves and fit various parts of the body, septic raw honey (not manufactures honey) is a potent anti-infection and anti-inflammatory natural product [5]. There are many folk remedies available, some might have a scientific explanation where others might live on myth passed from generation to generation.

When it comes to chamomile, it is known to help children suffering from colic and teething pain, but what about side effects associated to this natural plant? Well, I could find a few but nothing mentioning methemoglobinemia. I found mainly four toxic effects in humans caused by chamomile, 1) the normal allergic reaction in some individuals, 2) anaphylaxis (a life-threatening allergic reaction in people allergic to plants in the daisy family), 3) drowsiness, and 4) contact dermatitis [6].

Perhaps the biggest risk associated to the use of chamomile and vascular imbalance is the presence of coumarin (organic chemical compound) for its thinning effects. Coumarin has very mild blood thinning effects, though! Overall, I wasn't able to find any relation between methemoglobinemia and the use of chamomile.

If you know more about this issue, please help us build good knowledge on it by sharing your opinion in the comments section.

Cheers.

[1] Methemoglobinemia - Medline Plus, [http://www.nlm.nih.gov/medlineplus/ency/article/000562.htm], last visited on the 05th of December 2013, last update on the 31st of October 2013.

[2] Benzocaine topical - Drugs.com, [http://www.drugs.com/mtm/benzocaine-topical.html], last visited on the 05th of December 2013, last updated on the 01st of December 2013.

[3] Orajel, [http://www.orajel.com/], last visited on the 05th of December 2013, last update unknown.

[4] FDA warns... do not use this pain reliever... you could turn blue and die - Mercola], [http://articles.mercola.com/sites/articles/archive/2011/04/25/warning--fda-issues-alert-that-topical-anesthetics-may-kill-you.aspx], last visited on the 05th of December 2013, last update unknown.

[5] This bee product has enormous benefits for your health - Mercola, [http://articles.mercola.com/sites/articles/archive/2009/11/17/This-Bee-Product-Has-Enormous-Benefits-for-Your-Health.aspx], last visited on the 05th of December 2013, last update unknown.

[6] Integrative Medicine for Children, edited by May Loo, MD - June 2008.

[7] Web MD - Chamomile Herbal Information, [http://www.webmd.com/vitamins-and-supplements/lifestyle-guide-11/supplement-guide-chamomile], last visited on the 05th of December 2013, last update on the 13th of October 2012.