How much Botox is safe in one appointment? I'm having forehead, temple, masseter and fillers for the nose.

You should not exceed 100 units. You  should not need that much.  Fillers in the nose can work great and if not they are reversible.  

It's known from the Cerebral Palsy literature that 300units can be safely given in a child at one time. This is the limit I follow per 6mo period. This would typically be for patients who need masseter and calf slimming, along with some facial injections.

Hi Kayko.  We usually don't do more than 300 units of Dysport (100 units of Botox) in any appointment, not so much because we couldn't or wouldn't but because most patients do not want to spend more than that in one appointment.  Much, much higher doses are used safely when Botox is used for medical rather than cosmetic concerns so there should be no issues with your treatment plan.  Best of luck.