Attack of the Killer Mouthwash

“I read it in the paper so it must be true.”

-Jim Moriarity, Sherlock (2012)

Killer mouthwash? Ok, so maybe I’ve overstated my headline a little this time, but I may not be the only one. There’s a news story doing the rounds the last few days stating that “Mouthwash ‘could lead to greater incidences of heart attacks and strokes’.”


I managed to get my hands on the original journal article, and having read it the following things struck me:

1. The article was originally published in November 2012. If mouthwash is as dangerous as the headlines suggest, I would expect this to be news *much* sooner.

2. The study found an increase of between two and three mmHg in blood pressure after mouthwash use. (On average; some went up, some went down.) This is used to justify the claim of ‘increased risk of heart attacks and strokes’. But what really caught my eye was that the method they used to measure blood pressure was a digital blood pressure monitor made by Omron Corp.

And to quote from Omron’s website, “All OMRON Blood Pressure Monitors must meet stringent specifications for accuracy. Pressure: +/- 3 mm Hg.” In other words the blood pressure changes found in this study seems to be less than the monitor is actually capable of measuring to begin with.

3. The study looked at 19 people in one group, all using Corsodyl mouthwash. That’s a very small sample group. Most scientific studies also use a second group who would be given a “dummy” mouthwash at the same time. Why? Because otherwise you don’t know if you’re measuring the effect of the mouthwash, or something else. Maybe the group got stressed out as the study went on and their blood pressure went up. You can’t really tell in this study.

With two groups, you can compare them with each other and see what difference you find between the groups. (In fairness, the study acknowledges this weakness.)

It’s an interesting study, in a slightly obscure journal, but I think it over-reaches. When compared with the evidence we have that clearly links gum disease with heart disease, (a point also acknowledged in this study) I feel current evidence is still clearly in favour of mouthwash use.

Karl Cassidy - Dublin DentistWritten by .
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