Does vitamin C help us when we’re sick?

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By Jesse Bracamonte, D.O.
Posted on October 16, 2025

Dear Mayo Clinic: Growing up, I was told to drink orange juice when I had a cold because “vitamin C is the cure.” Does vitamin C actually help us when we’re sick? What are its benefits?

A: Vitamin C supports our immune systems, helps our bodies heal wounds, protects our joints and contributes to collagen formation, the main protein in the body. Vitamin C is an antioxidant that helps protect your cells against what are called free radicals, which are produced when your body is exposed to potentially cancerous things like cigarette smoke and the sun’s rays.

Despite all these benefits, there is limited evidence to support the notion that taking extra doses of vitamin C can effectively prevent common colds.

For most people, taking a daily oral supplement of vitamin C via tablets, drink powders or gummies may not be that beneficial because you might be getting it from your diet naturally. Our bodies don’t produce vitamin C on their own, but a lot of what we eat contains it.

Citrus fruits may come to mind first when we hear vitamin C, but foods such as potatoes, spinach, tomatoes, berries and other brightly colored fruits and vegetables are full of the nutrient. An orange bell pepper has three times the amount of vitamin C than an orange.

It’s important to get your daily intake of fruits and vegetables, but many people in the U.S. do not. A little bit of added vitamin C may actually help those individuals. In most cases, though, if you are able to access and eat an adequate supply of fruits and vegetables in your diet, that will be sufficient.

Some people may think they should double up on vitamin C supplements when feeling ill, but more is not always a good thing. Taking too much vitamin C can cause side effects that may make you feel worse, such as nausea, vomiting, stomach cramps, bloating, fatigue, heartburn, headaches, skin flushing and even kidney stones in some people. Make sure you do not consume more than the recommended daily dose of 500 milligrams.

High levels of vitamin C can also interfere with multiple kinds of medications and results of certain medical tests such as blood or glucose screening. For patients undergoing chemotherapy, the use of antioxidants such as vitamin C might lessen the effect of the chemotherapy drugs.

Overall, taking vitamin C in the form of food is the best way to reap its benefits, but taking extra vitamin C, particularly for those with a weakened immune system, would not be harmful.

Some limited research shows that vitamin C may shorten the duration of a virus, such as the common cold. So, if your cold lasts a week, a few limited studies found taking vitamin C may reduce it by 13 hours, which isn’t all that significant. Consult with your healthcare team to decide what’s best for you.

Jesse Bracamonte, D.O., Family Medicine, Mayo Clinic, Phoenix

Mayo Clinic Q & A is an educational resource and doesn’t replace regular medical care. This Mayo Clinic Q&A represents inquiries this healthcare expert has received from patients. For more information, visit mayoclinic.org.