• Lung problems : Symptoms of lung problems may include shortness of breath, cough, and fever. Erlotinib may need to be stopped if you have any of these symptoms
• Liver and kidney problems. Some people had their kidneys and liver stop working. Speak your doctor know if you have a history of liver or kidney disease
• Stomach and intestinal problems (called gastrointestinal [GI] perforation). A GI perforation is a hole that develops in your stomach or intestine. 
• Serious skin conditions. Erlotinib has been shown to cause blistering and skin peeling. This may result in other serious skin disorders or death
• Blood, bleeding, and clotting problems. Erlonat has been shown to cause certain blood problems and other bleeding and clotting problems. These have led to stroke and death.
• Eye disorders. It has been shown to cause dry eyes, unusual eyelash growth, or swelling of the cornea. The cornea is the clear coating of the eyeball. This swelling may irritate or damage the eye
• Pregnancy. Erlotinib can harm an unborn baby. Tell your doctor if you have become pregnant, or if you think you may be pregnant, during treatment with it. Do not breast-feed during treatment with it.

• Always tell your doctor about all of the medicines and herbal supplements you are taking
• Do not start taking any new medicines or herbal supplements before talking with your doctor
• Do not eat grapefruit or drink grapefruit juice .

• If you smoke, you should stop smoking before you start treatment with Erlotinib
• If you continue to smoke, your treatment with Erlotinib may need to be adjusted. Talk with your doctor if you continue to smoke

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects.