As the coronavirus pandemic continues, it’s easy to forget that we’re also in the midst of another national health situation — the annual cold and flu season. And it’s quite a season. Americans get more than 1 billion colds each year, according to the National Institutes of Health.

Not surprisingly, many people turn to supplements to help prevent and shorten colds. The two supplements currently atop the popularity heap are the perennial favorite, vitamin C, and the brash upstart, zinc. Before you take either, though, you should consider their effect on your mouth and your health.

Not necessarily. In fact, both supplements can be beneficial. However, each does have potential side effects you should be aware of.

First, the good. Vitamin C contributes to healthy gums. Your body also needs this vitamin to form the tissue that supports your teeth. And zinc can help improve your oral health by reducing the plaque that causes gum disease and cavities in your teeth.

Each has some downsides, though. Zinc can irritate your mouth and leave a lingering bad taste. It can irritate your stomach or make you nauseous. Zinc may also interact with drugs, including antibiotics and the rheumatoid arthritis medication penicillamine. Intranasal zinc, such as swabs and gels, has been linked to permanent loss of smell and should be avoided.

And avoid excessive doses of either. Vitamin C, taken in excess, can upset your stomach and cause abdominal pain. To avoid this, take less than 2,000 mg per day. High doses of zinc (150–450 mg) taken daily for long periods can negatively affect your immune system, reduce your body’s copper levels and lower your HDL, or “good,” cholesterol. To be safe, stick with 40 mg or less per day.

The answer according to the experts is, well, maybe. The jury on whether these supplements can actually prevent or reduce the severity of your cold is still out.

For our old friend vitamin C, the results are underwhelming. Research has found that vitamin C supplements don’t reduce the risk of getting a cold for most people, according to the National Institute of Health’s Office of Dietary Supplements, and taking a vitamin C supplement after you get a cold doesn’t appear to help much, either. Studies did find that taking vitamin C supplements regularly may shorten your cold or make its symptoms less severe.

The outcome for zinc is slightly better. While studies that have looked at the effect of zinc on cold symptoms have had mixed results, it appears that zinc may be beneficial. A small study found that zinc lozenges significantly reduced the length of cold symptoms, such as cough and muscle aches. A larger study found that zinc lozenges reduced the length of colds but didn’t reduce their severity.

If you’d like to avoid the possible negatives associated with supplements, you can seek out foods rich in zinc and vitamin C. Good sources of zinc include red meat, chicken, whole grains, beans and nuts. Vitamin C can be found in seemingly everything, including berries, potatoes, peppers, cabbage, Brussels sprouts, broccoli, spinach and, of course, orange juice. For more ways to get immune-boosting nutrients into your diet, check out some sumptuous soup recipes, or try a mouthwatering broccoli and red pepper frittata.