Maybe we should take a step back, and review how strong our minds are. If you are eating mostly natural-food, your body and mind will be working in homeostasis. When an illness befalls you, your mind will be able to heal you.
Our first move when feeling ill, should be to think “I feel great, I do not get sick”. Get your positivity going full force. If you still get sick, it happens. Start with all natural remedies; elderberry syrup, echinacea, purple, and citrus fruits, green and purple vegies, as well as herbal teas. Healing a cold through nature will take maybe 3 days, and you are not stressing your body. Healing a cold with synthetic drugs, will alter your body unnaturally while it heals you. This will actually make your body work harder, while healing. It has to fight synthetic changes while trying to maintain homeostasis.
Eat and medicate with what nature provides, stay positive, and I guarantee your happiness. When dealing with colds, flu, any disease really, mentally heal yourself. The placebo effect is real, and works as well as synthetic pharmaceuticals.