There comes a time every year when the flu season is at its peak and the virus circulating in the air makes inroads into your body and inflicts you with fever, sneezing and coughing. Although not life threatening, the cold and the flu can become a real irritant particularly because it drains your strength and confines you to bed. Being able to go to work becomes a distant possibility for a few days; in fact the continuous sneezing and sniffling robs you off your mental strength too, eventually forcing you to succumb to your sickness. The cold and flu virus therefore spells danger. However, a strong immune system can easily help to ward off this virus. Fortunately for us Mother Nature has made available certain herbs that can not only help to build up the immune system but their influence often renders the virus weak. This article gives a list of 5 such essential herbs.