Most of us have heard the common idiom “rub salt in a wound”. According to the Cambridge Dictionary, the phrase is used to describe making a bad situation even worse. For example, if you just lost your job and started clearing out your desk, only to have a coworker walk up and brag about his new promotion, he'd be rubbing salt in your metaphorical wound.
The origin of this idiom is easy enough to ascertain. If you've ever gotten seawater in a fresh cut, you'll know that literal salt in a wound can be physically painful. However, you may also recall that saline solution is used for wound irrigation in hospitals around the world. This got us thinking: it's obvious that rubbing salt in a real wound is painful, but is it really making a bad situation worse? Or could the salt make the situation better in the long term and prevent infection, becoming a viable technique for backcountry medicine?
Note: This article is not a comprehensive first-aid guide. Professional medical treatment should always be sought first before attempting any improvised treatments.
Historical linguists have indicated that the idiom came from a time when salt was used as an improvised antiseptic. “During the earlier centuries, when England was establishing its navy, most sailors were forced into service. While at sea, punishment was often lashes with a cat’o’nine tails. These whippings would almost always break the skin, and salt was rubbed into the wound to prevent infection. In this way, “salt in wound” was a very literal, stinging phrase.”
However, just because it was seen as a viable antiseptic back then doesn't mean it still is today. After all, we certainly don't use blood-letting, mercury, or lobotomies to cure our diseases these days.
In our search for an answer to this question, we found the following statement from Walter Sipe, M.D. of the University of California, San Francisco. He wrote the following response in 2006 in an Ask a Scientist column for the Howard Hughes Medical Institute:
Let me start by saying: Do not put salt on your cut. The single most important aspect of wound care in the backcountry is vigorous and copious irrigation with clean water (filtered or chemically treated so it is drinkable). You can generate a high-pressure stream by filling a zip-top plastic bag with water, poking a tiny hole in a bottom corner of it with a needle, and then squeezing the bag so water comes out through the hole. For dirty wounds, vigorous scrubbing to remove foreign bodies is also important. Exposing wounds to iodine, alcohol, peroxide, and pure salt is no more effective than water irrigation at preventing infection and can potentially damage tissues. The safest way to slow bleeding is to hold direct pressure on the wound until the bleeding stops.
Before you go thinking a dip in the ocean might be a better way of salting your wounds, scientists have found that rinsing a wound in seawater is harmful due to the presence of marine bacteria. Additionally, many dangerous bacteria have an extremely high salt tolerance and thrive in salty environments — Staphylococcus aureus, the bacteria behind potentially-deadly MRSA staph infections, is one notable example.
Finally, while it's true that sterile saline solution is used in many medical facilities, this solution contains a very small amount of dissolved salt for the purpose of mimicking your body's natural conditions. With regard to saline's antiseptic properties, multiple scientific studies have found that saline solution is no more effective for preventing infection than distilled water or even clean tap water. In fact, studies indicate that water may be preferable in some cases.
So, the conclusion is clear: next time you hear the phrase “rubbing salt in a wound”, remember that its metaphorical use of “making a bad situation worse” is also true in a medical context. It is not a viable technique for treating wounds in the backcountry. Doing so is likely to be very painful, may further irritate the wound, and it will not kill all the bacteria which might lead to a dangerous infection. Instead, keep the salt for your next meal, and irrigate your wounds thoroughly with clean purified or distilled water until you can seek professional medical treatment.