Get emergency medical help if you have signs of an allergic reaction: skin rash or hives; difficulty breathing; swelling of your face, lips, tongue, or throat.
Report any new or worsening symptoms to your doctor, such as: mood or behavior changes, anxiety, panic attacks, trouble sleeping, or if you feel impulsive, irritable, agitated, hostile, aggressive, restless, hyperactive (mentally or physically), more depressed, or have thoughts about suicide or hurting yourself.
Call your doctor at once if you have:
blurred vision, eye pain or redness, seeing halos around lights;
cough, chest tightness, trouble breathing;
a seizure (convulsions);
unusual bleeding--nosebleeds, bleeding gums, abnormal vaginal bleeding, any bleeding that will not stop;
low blood sodium--headache, confusion, problems with thinking or memory, weakness, feeling unsteady; or
severe nervous system reaction--very stiff (rigid) muscles, high fever, sweating, confusion, fast or uneven heartbeats, tremors, feeling like you might pass out.
Seek medical attention right away if you have symptoms of serotonin syndrome, such as: agitation, hallucinations, fever, sweating, shivering, fast heart rate, muscle stiffness, twitching, loss of coordination, nausea, vomiting, or diarrhea
Common side effects may include:
headache, dizziness, drowsiness, tiredness;
feeling anxious, nervous, or jittery;
sleep problems, unusual dreams;
tremors;
fast heartbeats;
blurred vision;
nausea, vomiting, diarrhea, constipation;
changes in weight or appetite;
dry mouth, yawning;
increased sweating; or
sexual problems.
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.
 Effexor XR side effects (more detail)
