Headaches are often caused by insufficient fluid intake.
Most often headaches are caused by dehydration, which you are not even aware of. Best recipe for removing the headache is to drink plenty of water. The pain will be gone soon.
When you are sick a glass or two of water can help in faster recovery and prevent dehydration.
If you can not drink enough water, try to compensate with fruits and vegetables. Numerous fruits and vegetables are rich in water. Watermelon, papaya, cucumber and celery are just some of them.
Their consumption is extremely useful in the prevention of dehydration.