Evidence-based pediatrics

Episode 1: Treating the common cold

There is still no viable remedy that consistently treats or prevents the common cold, and yet we spend close to $40 billion per year on products that claim to do so (1). If these treatments truly do nothing, why do they feel like they help so much?

Firstly, I should note that while none of them help our bodies heal any faster, a small minority of them do help us feel better by making us less aware of our symptoms. Ibuprofen, for example, reduces pain and fever, which makes us feel better. But in doing so, it may actually worsen the disease – albeit to a very minor degree (2). The symptoms of the common cold are actually our body fighting the virus. So whenever we reduce our symptoms, it makes sense that we might also be reducing the effectiveness of our immune response (plus adding side effects of treatment). Another example of this would be decongestants. They help us breathe better because they reduce the blood flow to our nose. But it is that blood flow that brings our immune response to the area, by reducing it we are decreasing the flow of our "troops" to the battlefield. 

Don't get me wrong, there is a huge role for things that help us feel better when we're sick – it's just important to be aware of what benefit we are or are not getting from therapies so we can use them more wisely. It also helps us compare them to other things that help us feel better but don't hinder the healing process – like a good movie and bowl of chicken soup.

The biggest category of treatments to avoid would be those that claim to heal or prevent the disease and/or make us feel better – but do neither. Unfortunately, that is the vast majority of cold remedies. And yet, they really feel like they work! Why?

The biggest reason is something called "regression to the mean." Most people start treatments on or around their worst day of illness – right when the illness has peaked and is about to start getting better anyway. Our brain has a powerful tendency towards pattern recognition, so even if the treatment wasn't responsible for the improvement, our brain links it together because the two happened at the same time. To illustrate this another way, if we eat a burrito and immediately get sick, our brain will link the thought of a burrito with an unpleasant feeling so we don't eat it again. Even if it wasn't the burrito that made us sick, (i.e. we caught a stomach virus from somewhere else by coincidence), our brain will still link it to the burrito because of the timing. So when our body experiences improvement while using a treatment – which it almost always will because of when we use treatments – our subconscious will "intuitively" feel it is helping us. That link is so powerful it's nearly impossible to convince us otherwise, just as it would be hard to convince us to eat another burrito until quite some time has passed! 

What about remedies that claim to prevent colds, like high-dose Vitamin C, Airborne, immune-boosters, etc.? This is a different phenomenon happening. Essentially, our brain artificially inflates how bad it imagines the disease would have been, and then is grateful that we only ended up with normal disease. It's a bit of circular logic, really. It starts with imagining a disease would have been worse than it was. Because the actual disease was in fact less than your expectation, that feeds back as validation that your original concern must have been true. This is especially cemented in our brains when every once in a while we have a very mild cold while happening to take a preventive remedy. If that cold happened to be 25% more mild than average, our brain may use it as a setpoint and assume that the remedy leads to a 25% reduction in cold symptoms. Now when you have an average cold after taking the remedy, your brain assumes it would have been 25% worse, and is grateful it was only average. It's kind of like marking up a product 25%, and then having a 25% off sale. Feels great!

Now, this is just scratching the surface, I would need to go into a lot more depth to cover all the nuances. I'll be touching on this topic in further posts, which may answer other questions you may have, so stay tuned. Suffice to say that intuition is incredibly powerful, though it can often lead us astray, especially in medicine. 

So how can we know when treatments actually do or don't work? Excellent question! On to part 2 (coming soon)...

For more details on treating the common cold, view my medical advice topic here.

1) http://www.marketplace.org/topics/life/cost-common-cold
2) Clinical Report—Fever and Antipyretic Use in
Children. Janice E. Sullivan, Henry C. Farrar et al. *Pediatrics*, published online Feb 28, 2011; DOI: 10.1542/peds.2010-385
3) For a great explanation of regression to the mean and other useful statistical concepts: "The Drunkards Walk: How Randomness Rules Our Lives" by Leonard Mlodinow.