Get emergency medical help if you have signs of an allergic reaction: hives; difficulty breathing; swelling of your face, lips, tongue, or throat.
Call your doctor at once if you have:
new or worsening chest pain;
chest pain spreading to your jaw or shoulder;
fast or pounding heartbeats;
swelling in your legs, ankles, or feet;
rapid weight gain, especially in your face and midsection;
shortness of breath;
a light-headed feeling, like you might pass out;
fluid build-up in the lungs--pain when you breathe, feeling short of breath while lying down, wheezing, gasping for breath, cough with foamy mucus; or
severe skin reaction--fever, sore throat, swelling in your face or tongue, burning in your eyes, skin pain, followed by a red or purple skin rash that spreads (especially in the face or upper body) and causes blistering and peeling.
Common side effects may include:
changes in color, length, or thickness of body or facial hair;
nausea, vomiting;
rash; or
breast pain or tenderness.
This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.
 Minoxidil side effects (more detail)
