As the days get shorter and cooler, the annual cold and flu season surely can’t be far behind. But this winter, it’s not going to get you—right? Assembling a natural tool kit now will ensure you’re prepared to prevent and self-treat the common cold and influenza. First, choose the most effective, science-based natural remedies; then pay close attention to timing and doses—how much to take and when.

Boost immunity

Start by reducing your risk of getting the common cold or flu, or at least minimizing the symptoms.

Vitamin D

Researchers believe wintertime susceptibility to the flu and colds may be related to less sunlight exposure and lower vitamin D production. Vitamin D regulates several germ-fighting immune factors, and recent studies show supplementing with D can cut the risk of contracting the flu.

Dose: 2,000 IU daily during fall and winter, or up to 4,000 IU if recommended by your health care provider after blood testing.

N-acetylcysteine (NAC)

This potent antioxidant boosts the body’s response to infection. In one study, Italian researchers found that seniors taking NAC had flu antibodies in their blood, so had been infected with the flu, but they exhibited virtually no symptoms.

Dose: 600 mg twice daily, or up to several grams daily if you do catch a cold.

Echinacea

An analysis of 14 studies published in The Lancet Infectious Diseases found that this popular traditional herb does help fight the common cold. And University of Connecticut researchers noted it reduced the odds of developing a cold by 58 percent, and helped speed recovery among those who did catch one. Dose:  Choose a standardized echinacea extract in tincture form; follow label directions.

Find relief

Be ready to aggressively fight a cold or flu on the first day you notice any symptoms, such as sneezing or achiness. Fast action can suppress viral replication and also modulate your immune response, which is responsible for many of the uncomfortable symptoms.

Zinc lozenges

In an analysis of 1,360 people in 15 studies, researchers reported that zinc lozenges do reduce the length of colds and symptoms—if people start taking them within 24 hours of their first cold symptoms. Zinc may work by inhibiting the growth of cold viruses.

Dose: As a general rule, suck on one 13-mg lozenge every two to three hours.

Vitamin C

Although vitamin C may not reduce your chances of contracting a cold or flu, research indicates it can reduce an infection’s symptoms and length.

Dose: Aim for 2,000–6,000 mg of C daily in divided doses; reduce dose if digestive upset results. If you have a sensitive tummy, opt for the gentler Ester-C form.

Elderberry

Antioxidant-rich elderberry extract can significantly reduce flu symptoms, including fever. According to The Journal of Alternative and Complementary Medicine, 90 percent of the people in a 40-person study experienced a “complete cure” within two to three days.

Dose: Opt for sugar-free elderberry syrup, and follow label directions for use.

Homeopathy

If you feel achy, try Oscillococcinum (pronounced os-sil-uh-cox-suh-num), a homeopathic remedy that can ease flu symptoms if taken within 48 hours of the first symptoms. Studies found significant symptom reduction after two days of taking the remedy, and a skeptical medical review acknowledged results were “promising.”

Dose: Follow label directions for use.

Recover

You may be able to reduce your supplements’ doses after a few days, but be careful. If your symptoms recur, you may be suffering from a temporary deficiency and need to maintain a relatively high vitamin C intake. To fight flu-related fatigue, consider adding coenzyme Q10 and L-carnitine, vitamin-like nutrients that naturally enhance energy production.