Is my mouthwash really going to increase my risk of death?

By Michelle Dickinson 28/01/2014

Well according to an article published in The New Zealand Herald on Jan 26th 2014 “Mouthwash is a Disaster for Health”.

The article (and several other International mainstream newspapers and news sites) claim that “using mouthwash is a ‘disaster for health’, increasing the risk of heart attacks and strokes”.

Is my mouthwash really going to harm me?

Is my mouthwash really going to harm me?

I stared at the harmless looking green bottle of liquid that brings me minty fresh breath each morning and wondered if it was really going to be the cause of my imminent death.

I have a Masters and PhD based in dental research and this was the first time that I had heard that rinsing with mouthwash could be a dangerous activity so I decided to investigate further.

Pulling out the scientific paper they refer to from the journal of free radical biology and medicine we can see that it was written by  group of scientists at Queen Mary University of London, headed up by Professor Amrita Ahluwalia.

Her group is interested in how mouth bacteria convert nitrate (NO3) into bioactive nitrite (NO2).  As certain types of antiseptic mouthwash have an active ingredient called chlorhexidine which kill mouth bacteria, she wanted to know if that has an effect on this nitrite conversion.

In her study she found that using Corsodyl mouthwash containing 2% chlorhexidine resulted in reduced levels of nitrite and increased levels of nitrate.  Nitrite is known to cause vasodilation or expansion of the blood vessels.  If the blood vessels get wider then blood pressure decreases (think of water pressure through a thin pipe vs a fat pipe).

Nobody knows why the blood pressure increased slightly but the thought is that the mouthwash reduced the number of ‘good’ bacteria in the mouth which reduce dietary nitrate (the bad stuff) to nitrite (the good stuff).

So this was a big scientific study….right?

If you read the paper you see that it is a very small study involving only 19 people who took their blood pressure for 7 days before using mouthwash, and then during the 7 days that they used 2% chlorhexidine containing mouthwash.

There was no control group in this study (people who had a placebo mouthwash), meaning that there is no way to tell if the act of swilling a solution around which doesn’t contain chlorhexidine has the same effect.  The group acknowledge that it was a small study, and that there was no placebo and no intervention during the 2 week study.  It doesn’t mean the research isn’t valid, but it is important to see that it’s a very small study involving healthy young people who do not use mouthwash on a regular basis.

 So, how is this going to kill us all?

Well to be honest, in my humble scientific opinion, I don’t think that it is.

The report states that even a small increase in blood pressure of only 2 mm Hg increases heart disease by 7% and stroke by 10%!

Wow, that sounds scary, and you could be led to the conclusion that mouthwash could increase your risk of both.  But looking deeper into the study, those numbers come from a 2002 paper published in the Lancet that looked at the medical records of 1 million patients aged between 40 and 89 years and determined risk factors associated with their age of death.  It found that in middle aged men (who may also smoke/drink/etc.) a reduction of 2 mm Hg in their blood pressure would reduce their risk of death due to stroke by 10% and risk of death from other vascular causes by 7%.

2 mm Hg is not very much, to put it in perspective, if a healthy male went for a gentle cycle his blood pressure increase would be around 19 mm Hg (although that would be temporary).

This is very different than what the media is reporting which seems to blanket those risks in all age groups and sexes based on mouthwash use.

Is my mouthwash going to harm me?

2% Chlorhexidine mouthwash is sold in small bottles and have the active ingredient listed on the front.

2% Chlorhexidine mouthwash is sold in small bottles and have the active ingredient listed on the front.

The type of mouthwash looked at in this study was not your general use mouthwash that you buy in the supermarket, but a very specific type containing 2% Chlorhexidine.  This type of mouthwash is sold at the pharmacy and specifically marketed for the short term treatment of bleeding gums, irritated gums, mouth ulcers, infections and post-surgery to promote healing.

It is not marketed as a daily use mouthwash, and it’s much  more expensive that the regular mouthwash brands so you probably wouldn’t get them mixed up.  There are some antiseptic daily mouthwashes that contain Chlorhexidine out there, but they contain only 0.06% and are specifically labelled for daily use.

So, if you are worried and want to avoid Chlorhexidine contain mouthwashes, take a look at the ingredients, if your mouthwash contains chlorhexidine it will typically come in a small round bottle and be priced around $14NZD.

Regular daily use mouthwash

Regular daily use mouthwash does not contain chlorhexidine and is typically sold in bottles that look like this.

Standard mouthwash typically comes in much bigger bottles that are less cylindrical  in shape and will cost around $8NZD.  These are readily available in the supermarket and may also contain fluoride.

So I’m going to keep using my regular mouthwash as part of my daily routine which also includes toothbrushing with a fluoridated toothpaste and flossing after meals and I’ll reduce my blood pressure naturally by reading less of these media scare stories!

If you want to hear my opinions on this article from the Paul Henry Show you can watch it here.