Commercial fragrances contain many chemical components and some of these use that same roadway to our nervous system. The exact method by which odours cause headaches and migraines is still being studied but there are several theories that exist.
Some researchers believe that strong odours cause blood vessels in the brain to pulsate, causing a headache or migraine.
There are however others that believe odours can stimulate parts of the brain and nervous system that are responsible for feeling pain in the head.
Olfactory chemical irritants that are smelled are transmitted by the sensory nerves and can cause negative effects such as a perfume headache on the system that causes headaches known as the trigeminovascular system.