I ate tylenol and benedryl daily for 20 years for sinus headaches. Grew up on prescription antihistamines since age 10. I was told by an immunologist that taking these every day was a bad idea. It seemed like a good idea to me! After I quit working in the hospital environment with all of the cleaning chemical exposures, and quit wearing makeup after ds was just born, and removed dairy and wheat from my diet due to his food intolerances, some time later I noticed that I never had headaches anymore! Years and years now---no more headaches.
As I added back wheat or dairy, or products with fragrances, and make up with synthetic chemicals, I noticed the headaches intensely again. So, I don't do that, mostly, lol.
I had had a CT of my head, saw an ENT, had full allergy testing, rounds and rounds of antibiotics, and was told nothing could really help the "vasomotor response". It wasn't migraines, just a constant stabbing ache behind my forehead.
Also, 96% of all sinus infections are fungal. And I have all kinds of reasons for fungal infections, with taking tylenol, benedryl and antihistamines and antibiotics all these years (plus a mouthful of mercury fillings). All of these mess with our detox pathways.
With all natural house and body care products, eliminating wheat and dairy and doing gut healing, I never have headaches unless I eat wheat/dairy (not sure which 'cause they always seem together). I do learn, but sometimes I don't listen to myself.