When XFactor first came out the most common side effects reported were joint pain, headaches, some cramping and rarely insomnia. I would have headaches for the first several weeks, then they would start to subside. For me, the headaches weren't worth the benefits so I stopped using Xfactor.
When XFactor Advanced came out I gave it a chance but I still got headaches from it. I found that supplementing with magnesium acetate helped with my headaches. Ever since, when running a XFactor cycle I would take magnesium acetate along with it. I would rarely get a headache and if I did it wasn't nearly as intense. This is when I would dose XFactor everyday.
I now only run Xfactor on workout days and dose it only preworkout. Occasionally I will still get headaches when taking 1 gram preworkout but dropping the dose to 750mg helps keep the headaches at bay. I haven't tried using magnesium acetate when dosing preworkout.
For people that suffer headaches when taking Xfactor preworkout only, I usually recommend trying a lower dose to see if that helps. If people are dosing everyday, based on my experience, I would first recommend trying a lower dose, if that doesn't work then running magnesium acetate with it may help.
I haven't tried magnesium acetate with the preworkout dosing protocol to relieve headaches but I will try it next time I run Xfactor.
I can't guarantee running magnesium acetate is the answer for everyone that gets headaches from ArA but it is cheap and I think it is worth a shot if lowering the dosage doesn't help.