Get emergency medical help if you have any of these signs of an allergic reaction to Zithromax: hives; difficulty breathing; swelling of your face, lips, tongue, or throat.
Stop using Zithromax and call your doctor at once if you have a serious side effect such as:
- diarrhea that is watery or bloody;
- headache with chest pain and severe dizziness, fainting, fast or pounding heartbeats;
- nausea, upper stomach pain, itching, loss of appetite, dark urine, clay-colored stools, jaundice (yellowing of the skin or eyes); 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.
Less serious Zithromax side effects may include:
- mild diarrhea, vomiting, constipation;
- stomach pain or upset;
- dizziness, tired feeling, mild headache;
- nervous feeling, sleep problems (insomnia);
- vaginal itching or discharge;
- mild rash or itching;
- ringing in your ears, problems with hearing; or
- decreased sense of taste or smell.
This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects.