What Can Go Wrong?

The risk in combining medications is that they may interact in a way that increases uncomfortable or harmful side effects. For instance, explains Dr. Ron Steingard, a child and adolescent psychiatrist at the Child Mind Institute, you can get overlapping side effects. If one medication causes mild sedation and the second does the same thing, the result can be so much sedation that the child isn’t herself and can’t stay awake.

Another type of interaction that can be problematic, Dr. Steingard adds, can occur if two medications use the same metabolic pathway — the mechanism in the body that breaks them down and delivers them to the target. If that pathway is overwhelmed, it can create a buildup of medication, causing the kind of side effects you’d see with a much higher dose of one of the meds.