My 5 year old just started tennex & he takes it at night just started yesterday, he is so drousy today, will the fatigue subside?

Tenex (guanfacine) side effects: are both drowsiness as well as lowering BP, so often started at night. The drowsy symptoms usually improve after several days, but if he is really fatigued, I recommend that you have his blood pressure checked to be sure that is ok. You do not state his dose, and he may well respond to a smaller dose. XS drowsiness will also affect focus, a reason for giving Tenex (guanfacine). Report his response to his doc.