What damage can Benadryl do?

Could you elaborate on the potential adverse effects of Benadryl? Are there any specific health conditions or individuals who may be more susceptible to these side effects? How severe can these effects be, and what steps should be taken if they occur? Is it SAFE to consume alcohol while taking Benadryl, and what about other medications or supplements? Is there a recommended dosage for adults and children, and are there any precautions to be aware of when administering Benadryl to children? Additionally, what are the long-term effects of prolonged or excessive use of Benadryl?