I have a stubborn case of scabiesand the physician prescribe

Patient: I have a stubborn case of scabies….and the physician prescribed stromectol. I am concerned about side effects…racing heart, etc. I want to take Benadryl to be safer regarding possible side effects of racing heart or eye problems. Is there a problem with taking Benadryl right before taking stromectol. I am concerned regarding possible side effects…racing heart or eye problems. Your opinion on benefits of taking Benadryl with this drug?