Training with a Cold - Scientific Review

A simple cold can interrupt any endurance training regimen. When every day contributes to building fitness, a loss of 7 to 10 days can seem like a profound setback. An article written in The Clinics of Sports Medicine (volume 26, issue 3), Dr. Clifton Page and Dr. Jason Diehl review diagnosis and treatment of upper respiratory infections in the athlete. They review the common cold along with sore throat and sinus infections.

Page and Diehl state that the common cold is the most frequent acute illness in the US and is the leading cause for missed days of work and school. For athletes, this frequently means missed days of training. Symptoms can include runny nose, fever, fatigue, sore throat, and cough. Not fun to have when you need to put in a 10 mile run or jump into an icy pool.
Unfortunately, this illness can last 5 to 14 days and is easily transmissable. Aerosolized particles coming from a cough or a sneeze are a great way to spread the illness. Moreover, the articles states that cold viruses could be isolated from the hands of 40% - 90% of affected individuals. Obviously, hand washing can reduce contagion.
What can an athlete do when he comes down with a cold?
"There is no evidence that antibiotics have a clinically important effect on colds uncomplicated by secondary infection. Symptomatic therapy remains the foundation of common cold treatment." The authors go on to further classify treatments and benfits. In summary, antibiotics, as mentioned before, do nothing to help. Antihistamines (Benadryl, Claritin, etc) and decongestants (Sudafed) "may be beneficial". Vitamin C, Echinacea, Zinc, and steam have unkown efficacy. A relatively new herb on the market, however, may show some benefit. Pelargonium sidoides, branded in the US as Umcka, has shown some benefit in reducing cold symptoms and duration. In an article titled "Efficacy of a pelargonium sidoides preparation in patients with the common cold: a randomized, double blind, placebo-controlled clinical trial" by

Lizogub, Riley, and Heger, they conclude that a preparation of this herb "represents an effective treatment of the common cold. It significantly reduces the severity of symptoms and shortens the duration of the common cold compared with placebo. The herbal drug is well tolerated."
Regarding training with a cold, Page and Diehl suggest "In settings with appropriate supervision, athletes who have viral URTIs [colds] and no fevers, myalgias [body aches], or symptoms below the neck are safe to continue their previous level of activity with no restrictions."