"Do not take Beta-blockers like metoprolol, atenolol and others, and Sympathomimetics together without talking to your health care professional. Examples of Sympathomimetics include stimulants or weight loss drugs like Amphetamine, Adderall, Dexedrine, Fastin, and Tenuate. Sympathomimetics also include some cough and cold products containing Pseudoephedrine (example Sudafed), Phenylephrine, or Phenylpropanolamine (PPA) and also herbal weight loss products containing ephedra or Ma huang. It is possible that Sympathomimetic drugs can cause chest pain, high blood pressure, increased heart rate or other heart-related side effects in persons predisposed to these conditions, which may make the Beta-blocker-type drug less effective at treating heart or blood pressure related problems."
This was listed as a severe interaction on AARP's drug interaction checker...