Phenylephrine HCl goes by the brand name Sudafed PE or Sudogest PE, according to WebMD. The medication decreases swelling in the nose and ears associated with colds, allergies, influenza and other respiratory infections.
Dizziness or lightheadedness, difficulty sleeping and excitability are among the most common side effects of phenylephrine, explains Everyday Health. Skin rashes and itching, appetite loss, and warmth, redness or tingling of the skin may also occur. More serious side effects requiring immediate medical care include fast or irregular heartbeat with palpitations, severe dizziness, severe anxiety, and easy bruising or bleeding, especially with flu-like symptoms.
This medication may also cause systemic allergic reaction requiring immediate medical care, notes Everyday Health. Symptoms include swelling of the face, lips, tongue or throat and difficulty breathing.