Does being cold increase your chances of catching the common cold?

Question

"Everyone knows" - a scary statement - that you get "a cold" from being cold. Now it seems to be a fact that you don't, because you get a cold from a (rhino)virus, not from the temperature.

But is there any correlation between temperature and disease?

I've seen claims that "cold lowers your immune system", and stuff like that, but no real evidence. As soon as you look into scientific research about this, you get claims that the correlation is not causation, because in the winter people spend more time inside (close to one another) for instance. (See for instance this article)

On the other hand - and I know this is a really bad form of reasoning -- I think if I'd go outside in the freezing cold wearing nothing but some summer pants, I'd not come out of that after a couple of hours like a happy camper. Is this non-sense, or is there some correlation between being cold (or even undercooled?) and disease? If so, how does this work?

Answer 1

Aside from the effect of cold temperatures on the human body, it's also important to consider the effect of cold temperatures on the virus.

One study found reduced virus infectivity at 37 degrees celcius while it was stable at 6 and 23 degrees.

And while we're at it, there's even more data on the flu. Quite a few studies found that "cold temperatures and low relative humidity are favorable to the spread of influenza virus."

So humidity is also important, as well as the interaction between humidity and temperature:

there seems to be some general indication that minimal survival for both lipid-enveloped [e.g. influenza] and non-lipid-enveloped viruses [e.g. rhinoviruses] occurs at an intermediate RH [relative humidity] of 40–70% (Arundel et al. 1986). Also, it is important to note that temperature and RH will always interact to affect the survival of airborne viruses in aerosols.

[Edit: In my initial answer I suggested that being cold doesn't make a difference to you. That's not quite true. It does seem to increase susceptibility to infection, though of course the point is that you do need to be exposed to a virus; you don't get a cold just from being cold.]

While temperature may have an effect on your susceptibility to infection, it also has an effect on the survival of the virus outside your body. They prefer colder (less humid) environments. This does mean you're more likely to catch a cold when it's cold, because the virus is more likely to survive and be transmitted.

Answer 2

From a 2007 review (Exposure to cold and respiratory tract infections by Mourtzoukou & Falagas):

… most of the available evidence from laboratory and clinical studies suggests that inhaled cold air, cooling of the body surface and cold stress induced by lowering the core body temperature cause pathophysiological responses such as vasoconstriction in the respiratory tract mucosa and suppression of immune responses, which are responsible for increased susceptibility to infections.

(Emphasis mine.)

Two things are worth noting:

• This review partly contradicts the conclusion in Solus’ answer, that “being cold doesn't seem to make a difference to you”. According to the review, it’s does. However, Solus’ answer is mainly concerned with influenza which is somewhat different from the rhinovirus so while his answer may actually be true, it almost certainly doesn’t apply to the common cold.

• This isn’t undisputed – there is also some evidence to other causes (notably Eccles (2002) and Brenner & al. (1999)). But most of the evidence points this way. Furthermore, the study by Eccles actually proposes a mechanism which isn’t that much different from the one above.

Answer 3

Latest study confirms that the chances increase due to a variety of factors diminishing immune response, at least in mouse cells:

Temperature-dependent innate defense against the common cold virus limits viral replication at warm temperature in mouse airway cells (Ellen F. Foxman, doi: 10.1073/pnas.1411030112)

... To gain insight into the mechanism of temperature-dependent growth, we compared the transcriptional response of primary mouse airway epithelial cells infected with rhinovirus at 33 °C vs. 37 °C. Mouse airway cells infected with mouse-adapted rhinovirus 1B exhibited a striking enrichment in expression of antiviral defense response genes at 37 °C relative to 33 °C, which correlated with significantly higher expression levels of type I and type III IFN genes and IFN-stimulated genes (ISGs) at 37 °C. Temperature-dependent IFN induction in response to rhinovirus was dependent on the MAVS protein, a key signaling adaptor of the RIG-I–like receptors (RLRs). Stimulation of primary airway cells with the synthetic RLR ligand poly I:C led to greater IFN induction at 37 °C relative to 33 °C at early time points poststimulation and to a sustained increase in the induction of ISGs at 37 °C relative to 33 °C. Recombinant type I IFN also stimulated more robust induction of ISGs at 37 °C than at 33 °C. Genetic deficiency of MAVS or the type I IFN receptor in infected airway cells permitted higher levels of viral replication, particularly at 37 °C, and partially rescued the temperature-dependent growth phenotype. These findings demonstrate that in mouse airway cells, rhinovirus replicates preferentially at nasal cavity temperature due, in part, to a less efficient antiviral defense response of infected cells at cool temperature.

Quoting one of the study authors (Akiko Iwasaki):

"Altogether," she added, "these temperature effects can result in an 100-fold difference in the level of cold virus" at 33C compared with 37C after three days - enough to turn an asymptomatic viral population into sneezing, runny-nosed misery.

Answer 4

The straight dope discussed this. It made the following points:

• The cold, wet feet, etc., don't make you more susceptible to the common cold.
• If anything, long stretches of cold temps mean you'll catch fewer colds, presumably because the germs die off
• We don't have indisputable evidence that winter is "cold season."
• Winter is flu season, but not always.
• Respiratory infections, setting aside colds and flu, seem to be more common in winter--but some think that's because of misdiagnosis (the article suggests that cold stress may be misdiagnosed as a cold)