Get emergency medical help if you have signs of an allergic reaction: hives; difficult breathing; swelling of your face, lips, tongue, or throat.
Stop using pioglitazone and call your doctor at once if you have symptoms of liver damage: nausea, upper stomach pain, itching, loss of appetite, dark urine, clay-colored stools, or jaundice (yellowing of the skin or eyes).
Call your doctor at once if you have:
shortness of breath (especially when lying down), unusual tiredness, swelling, rapid weight gain;
pink or red urine, painful or difficult urination, new or worsening urge to urinate;
changes in your vision; or
sudden unusual pain in your hand, arm, or foot.
Some people taking  pioglitazone have had bladder cancer, but it is not clear if pioglitazone was the actual cause.
Common side effects may include:
headache;
muscle pain; or
cold symptoms such as stuffy nose, sinus pain, sneezing, sore throat.
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.
 Pioglitazone side effects (more detail)
