Does vitamin C help with colds? Should you avoid milk when you're sick? Here's what works — and what doesn't.

We’re in the thick of cold and flu season, which always serves as a reminder that the common cold has no cure — hence why, when you inevitably catch one, you spend its entire duration (a whole box of tissues, more or less) fighting your way out with cold remedies that have circulated for generations. The thing is, there’s never any guarantee that those tips and tricks will work.

Because no one wants to waste their time or feel worse in pursuit of getting better, we asked some experts to clear the illness-laden air: Does vitamin C actually boost your germ-fighting ability? Is honey like magic for a sore throat or cough? Will milk really make your mucus thicker? Here’s a breakdown of everything to know about common cold remedies.

Vitamin C

Vitamin C is an antioxidant that “has been shown to have a positive impact on immune support,” says Michael Del Junco, a family medicine physician with Providence St. Joseph Hospital in Orange County, Calif., tells Yahoo Life. It works by stimulating the production and function of white blood cells, which are the body’s main barrier against infection. “Some studies suggest that vitamin C can help reduce the overall duration and severity of at-home cold symptoms. Evidence to support this, however, is not entirely consistent and does vary from study to study,” Del Junco explains.

The impact of vitamin C also varies from person to person, depending on their condition and choice of vitamin C supplementation (orange juice vs. an Emergen-C packet, for example), he adds. That said, it can’t hurt to ramp up your intake in the form of fruits and vegetables rich in vitamin C, such as guava, kiwi, oranges, bell peppers, strawberries, tomatoes and broccoli, he says. If you opt for a supplement form of vitamin C, David M. Brady, a naturopathic doctor and chief medical officer at Designs for Health, warns that concentrated doses may cause loose stools. If that happens, “the serving size should be reduced until these resolve,” he says.

Overall, vitamin C shines brightest as a cold preventative rather than treatment. And Del Junco says if you focus on getting enough of the nutrient in your daily diet, it can help keep you from getting sick in the first place.

Zinc

Although research on zinc and the common cold is plentiful, results regarding its efficacy are mixed. “Some research suggests that zinc supplementation, particularly when taken within 24 hours of the onset of cold symptoms, may help shorten the duration of the cold,” says Del Junco. Like vitamin C, zinc works in tandem with the immune system to support the function of protective white blood cells.

A 2021 analysis published in BMJ Open pooled data from 28 randomized controlled trials that explored whether zinc lozenges, gels, capsules or sprays could relieve cold symptoms or speed up treatment. It found that taking 75 to 100 milligrams of zinc daily at the first sign of a cold shortened the duration of symptoms by an average of two days and significantly reduced symptom severity. It’s worth noting that these results weren’t seen in all participants, though, which means there's no way to guarantee zinc supplements will help. However, there’s little harm in trying it, as long as you don’t exceed the recommended dosage, Del Junco says.

Echinacea

Echinacea is a common supplement that’s touted to help against colds. That’s because this native plant of North America is rich in flavonoids, alkylamides, phenols, and polysaccharides, all of which have protective functions within the body, says Brady. “Its roots and aerial parts have been used traditionally for colds, respiratory infections, bacterial infections and wound healing for centuries,” he says.

Scientific findings on the effectiveness of echinacea, however, are mixed. An older meta analysis, for example, found echinacea to help reduce duration and odds of catching a cold. Another study found it to reduce recurrent respiratory infection risk. On the flip side, a 2014 review of 24 double‐blind trials with 4,631 participants found echinacea products not to provide benefits for treating colds.

There are a couple of ways echinacea users choose to ingest the herb — the most popular being in dried tea and supplement forms. Just be aware that supplements like these are not regulated by the Food and Drug Administration, so it’s best to talk to your doctor before taking them.

Avoiding milk

Steering clear of milk and other dairy is common advice when you’re feeling sick. However, Del Junco says there is “no current evidence to support avoidance of milk during an illness,” adding: “I would recommend avoiding milk if you have lactose intolerance, but otherwise, milk is a great source of calcium and protein, which would be helpful during an illness.” That said, some people do report increased mucus with dairy consumption, he says, and if that's the case for you, skip it while you’re sick.

Honey for a sore throat or cough

“Natural honey has antibacterial, antiviral and antifungal properties,” says Del Junco. “It also has anti-inflammatory properties.” Here’s the catch: Drizzling it into tea could diminish its superpowers. “I recommend consuming honey during illness in its natural form,” del Junco says — a daily spoonful works. “Avoid heating the honey, because the heating process will denature the proteins and enzymes, resulting in a loss of enzyme activity,” he explains.

Don’t take this to mean you should avoid putting honey in tea entirely, though, especially if you find it soothing when you’re sick. Hydration, with which tea can help, is also an important aspect of cold recovery, “so there is no reason not to use it,” says Brady.

Regardless of which cold remedies you choose when you’re under the weather, Brady recommends running a humidifier to keep the lungs and nasal passages moist and working optimally. For Del Junco, there’s one solid recommendation he can safely give: the importance of maintaining a balanced diet, staying hydrated and practicing good hygiene, noting they’re essential for overall immune health.

“When you have a cold, your body tends to lose more fluids due to excess mucus production, fevers and sweating,” he explains. “Staying hydrated during this time can help alleviate symptoms and support your overall well-being.” You can make sure you’re getting enough by having broth-based soups, oatmeal, yogurt and smoothies. “Current guidelines are focused on increasing calories during the time of illness, due to increased metabolic demands,” he says. “In short, eat what you feel you can tolerate.”