While some supplements can be taken during the illness to ease symptoms and shorten illness duration, you may benefit more from taking these supplements daily, year-round.
Vitamin C
While it’s the subject of much debate, vitamin C may not help to actually prevent a cold. However, vitamin C does help boost immune system function, and there is evidence to suggest that taking high doses of vitamin C may help shorten the duration of your illness. It may also help ease some of the symptoms of your flu bug, acting as an antihistamine and anti-inflammatory to help dry up a runny nose, for example. One study found that reported flu and cold symptoms in a test group decreased 85 percent compared with the control group after being given a megadose of vitamin C.
Because vitamin C is essential to maximizing your immune performance, you should make sure that you’re getting your daily intake of vitamin C on a regular basis, and keep in mind that being sick, or under physical stress, can increase the body’s need for vitamin C.
If you’re feeling run down or feel that tickle in the back of your throat that signals that illness is imminent, double down on your vitamin C intake to decrease the total number of days you’ll be out of commission. You should look for a vitamin C supplement that contains bioflavonoids -- antioxidants found in citrus fruit, tea and other foods.
While there is no set dosage for vitamin C to treat colds or the flu, you can start by taking 1,000 to 2,000 mg every two hours for a period of six to eight hours, then scale back to taking the same dosage twice a day. Be mindful - high levels of vitamin C can cause bowel problems - so if you experience diarrhea, lower your dose. You should also taper off your vitamin C intake, rather than stopping it abruptly, to avoid “rebound scurvy” - a condition that can cause the gums to bleed.