You know the dangers of drowsy driving, buzzed driving, and texting while driving, but now you can add a new danger to the list: driving while sick. British parts retailer Halfords has been funding research on the topic, and so far the findings are nothing short of staggering.

By installing black boxes in test vehicles that record driving metrics such as acceleration, braking, speed, and lateral G-forces, researchers found that sick drivers–particularly those with flu-like symptoms–experience a 50% decrease in concentration, including slowed reaction times and a lower level of alertness. This is just as bad as drunk driving. In fact, Halfords, in association with British insurer Young Marmalade, publicized it as being just as bad as driving after having four double-whiskeys. Now, we don’t know how they pour their whiskeys in the United Kingdom–four doubles would surely put this author under the table–but suffice to say, being sick is a serious impairment when driving. To exacerbate the issue, flu season corresponds with the onset of wintry weather, meaning icy conditions are more likely, multiplying the risks of an accident.

How Prevalent is This?

As long as you’re not sick, you don’t have anything to worry about, right? Surely there can’t be very many sick drivers on the road. Wrong. According to Flu.gov, 5-20% of the population gets the flu each year–that’s 1-5 out of every 20 drivers. And what’s more, Halfords found that 40% of people admit to driving to work while sick. Put those two figures together, and during the height of flu season, you’re virtually guaranteed to come across sick drivers all the time.

OTC Medications Increase Risk

If driving while sick in wintry conditions weren’t enough, there’s the added danger caused by common flu and cold medications. Many of these cause drowsiness, and even over-the-counter medications can cause impairment equivalent to drunk driving. While it’s difficult to pinpoint any concrete accident statistics from “drugged driving,” the FDA does maintain a list of active ingredients that make it unsafe to operate a vehicle. This includes common ingredients such as codeine and naproxen. Prescription medications are even more dangerous, as they tend to be more powerful. Keep in mind, safety isn’t the only issue. It is possible to get a DUI from legal drugs.

The Killer Sneeze

You don’t have to be plagued with the flu to be a danger on the roads. One of the most dangerous aspects of sick driving is also common among the healthy: sneezing. In fact, Halfords estimates that sneezes cause 2500 accidents in the UK…per week! The reason is simple. When you sneeze, your eyes close, involuntarily, for 600 milliseconds. That might not sound like very long–a little more than half a second–but at 65 mph, you’ll travel some 57 feet with your eyes closed! That’s right, almost 20 yards!

Got the Sniffles? Stay Home!

If you have a heavy cold, the flu, or flu-like symptoms, it’s best to stay home. In fact, representatives from Britain’s Central Motorway Police Group have stated just that in the wake of these findings. While your boss may not give a hoot what the bobbies have to say on the subject, he or she probably doesn’t want you getting the rest of the office sick. So stay home if you can, and if you can’t, get someone to drive you to work.

Author Taylor Brown is an automotive enthusiast who maintains this blog at Motive Auto Finance.