For centuries there has been the idea in various countries that people get sick if exposed to low temperatures, especially if it is wet. But, as many doctors will have already told you, the common cold is transmitted by a virus. So, if you just bathed and you must leave the house urgently should you worry about doing it with wet hair?
Studies in Germany and Argentina have found a high incidence of colds in winter, while in warmer countries such as Guinea, Malaysia and The Gambia, the highest peaks of the disease occur during rainy seasons. We can conclude from these studies that cold or humid weather cause colds, but there is an alternative explanation.
Scientists conducted experiments in laboratory conditions where they lowered the temperature of volunteers and deliberately exposed them to the cold virus. But in general, the studies have not been conclusive. Some found that the group under low temperatures was more likely to succumb to the disease, but others found that it was not.
However, a study carried out in a different way offers the intriguing suggestion that there might be some truth after all.
Ron Eccles, director of Common Cold Center in Cardiff, UK, wanted to know whether the virus is activated by cold and humidity, which in turn causes sneezing and coughing. To do this, the study subjects were subjected to a temperature cool down in the laboratory and then returned to their normal life and mixed with people, including those who had the virus in their body but without symptoms.
Half of Eccles’ volunteers had to sit with their feet in cold water for 20 minutes, while the other half did so by keeping their socks and shoes but feet in an empty container for the same period of time. There were no differences in reported cold symptoms in the two groups in the first few days, but four or five days later twice as many people in the cold water group said they had developed a cold.
For this to make sense it is necessary that there be a mechanism that will cool the feet or, what could be an equivalent, have wet hair, which could generate a cold. One theory is that when your body is exposed to cold the blood vessels of the nose and throat contract. When this happens, fewer white cells (your defenses against the virus) reach the nose or throat leaving you defenseless. When the hair dries or you enter the house, your body heats up again, your blood vessels dilate and the white cells again have the free passage to fight the virus. But by then it could be too late and the virus could have had enough time to replicate and trigger the symptoms
Then, according to this theory, the cold is not the cause of the cold, but could activate a virus that was already present in the throat. Keep in mind, however, that this theory is controversial and the Eccles study only showed that more people who had been exposed to cold said they had symptoms of a cold, but no medical tests were done to confirm that they were definitely infected with the virus .
And you do you think? Are you the one who comes out with wet hair and does not get sick? Or, on the contrary, you always dry your hair before you leave. Tell us!