As the temperature dips lower in January and February we often encounter an expected but not exactly welcome house guest -- the winter cold, or the even more demanding and obnoxious visitor, the flu. The cold brings a headache, sore throat, congestion, runny nose, sneezing and exhaustion. If it's the flu, you can plan on body aches and a fever along with everything else. Naturally, you want to get rid of these guests as soon as possible.

The common cold is caused by any one of around 300 different viruses. These viruses evolve and mutate from one season to the next, which is why it's impossible to develop a single vaccine effective against them all. Over-the-counter medications can't prevent the common cold or flu either. In fact, over the long term, these medications can often make matters worse. Decongestants and antihistamines may treat obvious cold symptoms, but not the underlying infection. On top of that, they can actually suppress the body's natural response -- fevers, sneezing, coughing, etc. -- to rid itself of an unwelcome intruder.

No one wants endure an untreated cold or flu. Thankfully, there are natural ways to strengthen your immune system and shorten a cold's duration and severity. Prevention is always better than cure, and a strong immune system is the best defense against all infections. So here are some of the most useful natural remedies that can make the difference between winter well-being, and a lot of Kleenex and misery.