Lemon (rich in Vitamin C) is used to treat common cold, as it increases the body resistance. Take one glass of luke warm (not hot) water, add a little lime juice and 1 tsp of honey. Consume it once or twice for 2-3 days.
Peeper powder can also be used. Take 1 tbsp of pepper powder and boil it in a cup of milk. Add a pinch of turmeric and sugar for taste. Consume once in a day for 2-3 days.
Onion juice is also very effective to cure cold. Grate a big onion, strain to have 3-4 tsp onion juice. Mix 3-4 tsp honey and mix well.
Garlic Soup is an old remedy (as suggested by my grandmother). Boil 4 cloves of garlic in a cup of water and strain.
Ginger can also be used to cure cold. Boil 10 gms of chopped ginger in a cup of water and strain. Consume the hot soup with 1/2 tsp of sugar added to it. You can even have ginger tea by adding chopped ginger before adding the tea leaves.