When discontinuing treatment, or decreasing dosage, patients should work with a doctor to gradually taper the level of medication by no more than 1mg every 3 to 7 days. Stopping guanfacine suddenly can create
withdrawal symptoms including increased heart rate and high blood pressure, sometimes accompanied by headaches, confusion, agitation, or tremors."
This and the other quote is from.... https://www.additudemag.com/medication/guanfacine/
I hope this helps.