Should you continue fasting if you get sick? If you happen to get sick while fasting it is wise to stop for a while until you get better before proceeding with the fast. This way you will prevent unnecessary medical complications which might lead to severe consequences.
However, if it is a minor headache and you are convinced it won’t bother you, then you should proceed with your biblical fasting. Sometimes these can be a distraction from the enemy to deter you from your spiritual obligation as a Christian. You should be able to discern whether it is a distraction or a real medical complication.
If it is your first time to fast, your body will tend to resist the new conditions you are subjecting it to. As a result, you might experience minor headaches and body weakness. You have to be wise to overcome the temptation to break a fast because of your appetite.
On the contrary, if you have been having health issues before, you should seek advice from a doctor. Biblical fasting is not meant to punish you; therefore, you should not endanger yourself to prove a point. God knows your heart. If you have enough faith, you should pray and fast yourself out of any situation, but not all Christians have faith.
Remember I am not a doctor, so if you have complications during a fast please seek advice from a physician. My desire is that you should build your faith to come out of any challenge you face in life.