Now that cold and flu season has arrived, you’ve likely begun hearing a lot about popular immune system helpers like echinacea, goldenseal, zinc and vitamin C — and for good reason. Years of solid research show that these natural remedies can help prevent a viral infection taking hold, and ease symptoms when one does slip by. However, a few lesser-known remedies are now joining the ranks of powerful cold and flu fighters due to impressive research in the area of immune system health.

Andrographis

Sometimes called “Indian echinacea” this herb was reportedly used during the Indian flu epidemic of 1919 and was credited with helping to curb the spread of the disease. A 2004 meta-analysis of seven double-blind trials concluded that andrographis was effective in reducing cold symptoms. In one of these trials, people given andrographis experienced significant improvements in symptoms compared to those taking a placebo. The greatest response was seen in earache, sleeplessness, nasal drainage and sore throat, but other cold symptoms improved as well. Andrographis also appears to prevent colds, too. In one trial, the herb reduced the risk of catching a cold by 50% among a group of students.

Elderberry

This remedy is certainly not new — it’s been used for centuries in folk medicine as a remedy for colds and flu, and researchers are finally determining why. “This herb contains two compounds that are active against flu viruses,” says Dr James Duke, renowned herbalist and author of The Green Pharmacy. “It also prevents the virus from invading respiratory tract cells.”

Duke cites a research trial in which 20% of flu sufferers experienced relief from fever, aches and other symptoms within 24 hours of taking elderberry. By day two, 73% felt better and by the third day, 90% were reported to be completely cured. The usual course of the flu is six to 10 days.

NAC (N-acetyl-cysteine)

An altered form of the amino acid cysteine, NAC appears to diminish the ability of viral cells to replicate. It can also help reduce cough, improve clearing of phlegm, and can raise levels of glutathione, the body’s own natural antioxidant which is vital to the immune system. Taking NAC during cold and flu season may prevent infection, or help ease symptoms. In one study of 262 patients who took NAC or placebo throughout cold and flu season, NAC significantly reduced the number who developed symptoms — even though they had been exposed.

Sources: Planta Med. 2004;70:293-8; Phytomedicine. 1999;6:217–223; The Green Pharmacy by J Duke, St Martin’s:1997; Eur Respir J. 1997 Jul;10(7):1535-41