Hi if the head ache is mild then no need to worry. Usually it will disappear in time. Body needs adjustment with this drug and depends on individual body. It may disappear in 2 day or may take more than a week.
If this persists or if he develops severe head ache or any of the following symptoms like Abnormal muscle weakness
or tiredness, severe allergic reaction
, Changes in vision, Blurred vision, Dyspnea (shortness of breath
), Syncope (fainting),or severe chest pain
then you are required to consult your doctor for dose adjustment or to change the drug.
Hope this helps.