Get emergency medical help if you have signs of an allergic reaction: hives; difficult breathing; swelling of your face, lips, tongue, or throat.
Call your doctor at once if you have:
chest pain;
pounding heartbeats or fluttering in your chest;
easy bruising or bleeding;
a light-headed feeling, like you might pass out;
liver problems--nausea, upper stomach pain, itching, tiredness, loss of appetite, dark urine, clay-colored stools, jaundice (yellowing of the skin or eyes);
low potassium--leg cramps, constipation, irregular heartbeats, fluttering in your chest, increased thirst or urination, numbness or tingling, muscle weakness or limp feeling;
low levels of sodium in the body--headache, confusion, slurred speech, severe weakness, vomiting, loss of coordination, feeling unsteady;
other signs of an electrolyte imbalance--dry mouth, nausea, vomiting, weakness, drowsiness, lack of energy, muscle pain, little or no urination, or feeling restless; 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:
dizziness, spinning sensation;
drowsiness, tiredness;
depressed mood;
muscle or joint pain;
numbness or tingly feeling;
nausea, stomach pain, loss of appetite; or
diarrhea, constipation.
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.
 Metolazone side effects (more detail)
