Oddly enough, I get at least a mild headache ANYTIME I've used a new growth aid on my head.
Usually, it feels like lightheadness more so than sinus, and I've always thought it was because most growth aids stimulate your circulation somehow, and all the blood was rushing to my head. Or, all that massaging did it.
Anyhow. I've gotten headaches for the first couple of uses for all of them - Lenzi's Request, MT, MTG (that one might have been from the smell), Sweet Success oil, coffee oil - I think at this point, if my head didn't start to feel a lil swole after using a topical growth aid, I would assume it wasn't doing anything.
Anyhow. I know my body, and the headaches have never concerned me/made me uncomfy, so I continued using the products (except MTG.
). I would think that if it persists, for more than 3-5 uses (that was my personal cutoff) - I don't know. I might have to reconsider using it - long hair ain't worth a consistently sore head.
One thing I found to help, was to massage my head, starting from the nape of my neck, and working forward, keeping my shoulders and jaw and neck very loose the whole time. Besides feeling just SOOO yummy, the headaches always eased, too.
G'luck!