Fasting headache: what should you know?

During a fast, a long gap between meals may leave you low on readily available energy. The body can also react to less water, sweating, poor sleep, or a sudden change in usual caffeine intake. The pain may feel dull, throbbing, or tight and can occur with hunger, weakness, dizziness, irritability, or difficulty concentrating. A headache during fasting does not by itself identify one particular condition. Dehydration and heat exhaustion are possible contributors, especially in hot weather or after exercise. Congestion from allergic rhinitis, chronic sinusitis, or a common cold can also cause head or facial pressure while fasting.

Move to a cool place, rest, and follow the fasting plan given by your clinician or religious adviser. When you are able to drink, take fluids gradually; when the fast ends, choose a balanced meal and avoid eating very quickly. Reduce strenuous activity in heat and keep a record of when the pain begins, what you drank, sleep quality, caffeine intake, and any other symptoms. Do not change medicines or fast through symptoms if you have diabetes, are pregnant, take regular treatment, or have been advised to avoid fasting. A pharmacist or clinician can help you choose a pain reliever that fits your health history.

Seek urgent medical help for a sudden severe headache, fainting, confusion, weakness on one side, trouble speaking, a stiff neck with fever, repeated vomiting, vision loss, chest pain, or difficulty breathing. Arrange prompt assessment if the headache follows a head injury, keeps returning, or does not settle after fluids, rest, and eating when appropriate. Fever, marked thirst, very little urine, worsening dizziness, or inability to keep fluids down can signal significant dehydration. A clinician should assess a new headache in someone with an immune problem or another serious medical condition.

Could my medicines, caffeine routine, blood sugar, blood pressure, or another condition be contributing? Is fasting suitable with my medical history, and how should I plan fluids, meals, and treatment? Which symptoms mean I should stop fasting and seek help?