Sympathomimetic decongestants like Phenylephrine and Pseudoephedrine can:
- Elevate blood pressure
- Elevate intraocular pressure,
- Worsen existing urinary obstruction (in elderly patients), and
- Adversely interact with β-blockers, methyldopa, tricyclic antidepressants, oral hypoglycemic agents, and MAOIs.
- Speed up the heart rate