The Sad Truth Behind Taking Vitamin C and Zinc for Colds

Cold season has descended upon us. You’ve got to shake these chills. You’ll do anything if there’s hope of some release from the discomfort of your booger-filled face.


Two cold “remedies” might come to mind (aside from grandma’s chicken soup), namely zinc and vitamin C. But here’s something you probably don’t want to hear: Science doesn’t support these remedies’ effectiveness the same way your parents might.

Vitamin C and zinc lozenges have both been around as cold remedies for several decades, and have been subject to many clinical trials. Scientists have since compiled these studies into meta analyses, or larger studies pooling the data from all the smaller ones to make some sort of larger conclusion.

The verdict? These many studies trend towards no to slight benefits, depending on a person’s circumstances.

More specifically, vitamin C doesn’t seem to have any benefits if taken once the cold symptoms start, as you would with something like Emergen-C. And even if it’s taken as a regular supplement, 29 studies found it didn’t seem to decrease your chances of getting a cold.

However, looking at just five of those 29, there was a decrease in the chance of getting a cold for folks who do a lot of physical activity, like marathon runners. And 31 other studies found that regular supplements (again, not just a heavy dose of vitamin C once the cold starts) could decrease the length of a cold.

The verdict? Well, it might be worth taking a regular vitamin C supplement if you’re worried. And while a shot of Emergen-C won’t do any harm, it might not do any good either.


As for zinc, the picture is similarly as hazy. Thirteen trials suggested that, with a high enough dose, zinc could shorten the length of a cold. But scientists haven’t figured out what that does as yet. And you don’t want to take too much—overdosing can lead to gastrointestinal troubles like vomiting and diarrhea.

Ultimately up to you to determine whether you’ll go for one of these treatments when that scratchy feeling starts to pop up in your throat. But guaranteeing a sure-fire cold cure would be shit advice.


Former Gizmodo physics writer and founder of Birdmodo, now a science communicator specializing in quantum computing and birds


Fun Fact: Nobel Prize winning biochemist Linus Pauling championed vitamin C as a preventative and palliative for the common cold. In a hearing he showed two test tubes, one empty and one full. Holding up the empty one he said “This is how much vitamin C the human body synthesizes in a day, and...”, holding up the full one “...this is how much a goat synthesizes. I think the goat knows more about it than we do.”

Funner fact: Pauling also won the Nobel Peace Prize for his activism in nuclear disarmament. He is one of only four to win multiple Nobel Prizes, and the only one to win two un-shared Nobel Prizes. He is rated in the top 20 scientists of all time.