Hello, You have headaches when you are tired and when you go for shopping for 2-3 hrs. Dehydration is one of the common cause of headaches. Dehydration headaches subside within a few hours after drinking water. To prevent headache and fatigue caused by dehydration take 8 to 10 glasses of water a day. Hormonal changes before and during menstruation can lead to headache as well as fatigue. Limit the amount of caffeine intake, caffeine can interfere with sleep if you consume too much. Poor sleep can lead to fatigue and headache. You may experience withdrawal symptoms, which include both headache and fatigue. Lack of sleep causes high cortisol level thus causing fatigue and headache along with irritability. Take food properly, home made food rich in iron, calcium and protein, do not skip meals. Being anemic causes the body’s tissues to get insufficient oxygen causing you to feel fatigued and weak. Digital eye strain also causes fatigue or tiredness may cause problems sleeping, which could cause you to become even more fatigued. Looking away from your screen every 20 minutes to something that’s at least 20 feet away, for at least 20 seconds may be helpful. Certain medications like diuretics, certain blood pressure medications have side effects that lead to headache and fatigue because they can make you dehydrated. You can take acetaminophen, one stat after food to get relieve. Get clinically examined by an eye specialist to detect any vision problem that may be causing you headache. You may need a pair of looking glasses. Take care. Hope I have answered your question. Let me know if I can assist you further. Regards, Dr. Nupur K., General & Family Physician