Can you overdose on cold supplements?

April 27, 2018 Swedish Blogger

close up of various types of pills


In this article:

  • Vitamin C is not proven to cure or prevent colds.

  • Mega doses of vitamin C or other vitamins may lead to unpleasant side effects.

  • Talk to your Swedish physician about potential side effects or interactions with your medications before taking supplements.

In 1970, Linus Pauling declared mega-doses of vitamin C the cure for the common cold. Pauling was a famous molecular biologist, a contributor to the discovery of DNA, and the only person ever awarded two non-shared Nobel prizes. In short, his pronouncements carried weight.

Over the years, science has come to regard Pauling as overly optimistic, the prevailing consensus being that prevention of scurvy is the only physiological effect of vitamin C. 

But that didn’t stop Airborne and Emergen-C from marketing mega-dose supplements with vitamin C as cold remedies. Instead, it took multimillion-dollar lawsuits to get both companies to re-label their products as “immune boosters” and resolve allegations of deceptive marketing practices

If this were the only problem with these supplements — that they purport to cure a cold, but with no conclusive evidence to back up the claims — we could simply chalk it up to misleading advertising and get on with our lives. But there may be a more cautionary aspect to the story.

What’s in Airborne & Emergen-C?

Adequate vitamin C is a generally accepted component of a healthy, well-balanced diet. The recommended dietary allowance for adults is 65 to 90 milligrams per day — easily obtainable by eating an orange, a cup of broccoli or any other food rich in vitamin C.

However, Airborne and Emergen-C tablets each contain 1000 milligrams. Two tablets deliver a 2000 milligram mega-dose — the very top of the tolerable daily limit for most healthy adults. And dosage directions typically suggest 1 tablet every three to four hours, up to three tablets a day. That’s over 65 times the recommended daily intake.

Taking such high mega-doses of vitamin C — even just for a few days — can have rather unpleasant side effects including gastric distress (indigestion, diarrhea, stomach cramps), nausea, headache and insomnia.

And that’s just the vitamin C. 

Airborne also contains very high doses of vitamin A and vitamin E, as well as zinc, magnesium, selenium, echinacea and Chinese herbs like vitex. Excessive consumption of vitamin A has been linked to everything from relatively benign symptoms like sluggishness, vomiting, and severe headaches to more serious conditions like liver damage and bone loss. High doses of vitamins are especially problematic for pregnant women, exacerbating the already elevated risk of osteoporosis. 

The side-effects of many other ingredients in Airborne and Emergen-C have simply not been studied in any systematic way to the point where experts can conclusively say whether they are dangerous or not. 

Part of the problem with these products is that they are sold as over-the-counter supplements for a temporary immune system boost when you feel a cold coming on or you’re preparing to travel on an airplane or be around large numbers of cold-carrying fellow travelers. As a result, people are often very cavalier about dosage recommendations — even people who would normally be compliant with prescription medications.

To make matters worse, Airborne and Emergen-C now come in gummy form. Aside from the inherently higher sugar content — a long-term health risk in itself — it’s easy to take more than the recommended daily dose when it feels like you’re just eating candy.    

So, can you overdose on cold supplements? 

Overdose is a loaded term.

It’s usually associated with life-threatening, if not fatal consequences.

It’s definitely possible to consume enough cold supplements to cause mild to moderate side effects. Moreover, the practice of vitamin C mega-dosing as a cold remedy is not conclusively supported by the evidence to date. And the effect of so many other cold supplement ingredients is unknown at best.

Given these facts, the real question is “Why are people still taking these supplements at all?” On the other hand, when taken by otherwise healthy adults in conjunction with their doctor’s advice they may be worth a try. 

Learn more about herbals that may help the common cold and trustworthy resources for medical information about supplements and cold therapies.

Talk with your doctor about potential side effects and interactions of the medicines and supplements you are taking or plan to take. Find a Swedish doctor near you.

Find a doctor

 If you have questions about which supplements you may need, contact the primary care department at Swedish. We can accommodate both in-person and virtual visits.

Whether you require an in-person visit or want to consult a doctor virtually, you have options. Swedish Virtual Care connects you face-to-face with a nurse practitioner who can review your symptoms, provide instruction and follow up as needed. If you need to find a doctor, you can use our provider directory.

Join our Patient and Family Advisory Council.

 This information is not intended as a substitute for professional medical care. Always follow your health care professional's instructions.

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