Furthermore, exposure to allergens (items to which you are sensitive) causes your immune system to release particular molecules. They can cause inflammation throughout your body, which can lead to migraines. If you suffer from migraine headaches, your symptoms may worsen during allergy season. Allergy-related sinus problems and nasal congestion can also contribute to headaches. Headaches are the most common symptom of allergies, so it makes sense that they would occur together. Actually, statistics show that about 80% of people who experience allergic reactions to certain foods, insects, or chemicals also have head pain every time their bodies are reacting to these substances. The most common type of headache associated with allergies is called an allergic reaction. This type of headache occurs when your body reacts to something you were exposed to earlier in the day. For example, if you ate a food product you're not used to, your body will react by sending signals to your brain asking for help. These signals will eventually lead to the production of hormones such as histamines and serotonin. Serotonin is known to be connected with feelings of well-being and happiness, while histamines play a role in causing inflammation throughout the body. People who suffer from allergic reactions to certain items tend to have more frequent headaches. This is because your body is trying to rid itself of these substances in order to return to its normal state.