When should I tell my doctor about problems with phenobarbital?

If you are taking Phenobarbital, you may have side effects that go away after you get used to it. If side effects like nightmares, constipation or muscle and joint pain continue, let your doctor know. Call your doctor right away if you have any of the following:

  • bloody nose
  • sore throat
  • bad skin rash
  • fever
  • bruising
  • mouth sores

Call 911 for:

  • breathing problems
  • difficulty swallowing
  • seizures