Medicine for Headache?

What medicine do you take when you have a bad headache? A paracetamol? What is headache? It is an effect. There is something else that is causing it. The cause could be one of the following or something else:

A major deficiency and its treatment!

A Deficiency is defined as: lack or shortage of something that is essential. Example: Doctors prescribe vitamin tablets to treat the condition. Mothers make sure children have balanced diet so don't become deficient of any essential nutrient.