This medicine may interact with the following medications:

-antiviral medicines for HIV or AIDS
-boceprevir
-certain antibiotics like ciprofloxacin, clarithromycin, erythromycin, telithromycin
-certain medicines for fungal infections like itraconazole, ketoconazole, posaconazole, or voriconazole
-certain medicines for seizures like carbamazepine, phenobarbital, phenytoin
-certain medicines for stomach problems like cimetidine, famotidine, omeprazole, lansoprazole
-certain medicines for tuberculosis like rifabutin, rifampin, rifapentine
-certain medicines that treat or prevent blood clots like warfarin
-conivaptan
-grapefruit juice
-nefazodone
-St. John''s Wort
-teriflunomide

They need to know if you have any of these conditions:

-dehydration
-eye disease, vision problems
-kidney disease
-liver disease
-lung or breathing disease, like asthma
-stomach or intestine problems
-an unusual or allergic reaction to erlotinib, other medicines, foods, dyes, or preservatives
-pregnant or trying to get pregnant
-breast-feeding

Tell your doctor or healthcare provider if your symptoms do not start to get better or if they get worse.

This medicine may cause serious skin reactions. They can happen weeks to months after starting the medicine. Contact your healthcare provider right away if you notice fevers or flu-like symptoms with a rash. The rash may be red or purple and then turn into blisters or peeling of the skin. Or, you might notice a red rash with swelling of the face, lips, or lymph nodes in your neck or under your arms.

Visit your doctor for regular check ups. Report any side effects. Continue your course of treatment unless your doctor tells you to stop. You will need blood work done while you are taking this medicine.

Tell your doctor or healthcare provider right away if you have any change in your eyesight.

Check with your doctor or healthcare provider if you get an attack of severe diarrhea, nausea and vomiting, or if you sweat a lot. The loss of too much body fluid can make it dangerous for you to take this medicine.

If you smoke cigarettes, you should stop smoking. The effectiveness of this drug is reduced by cigarette smoking. If you stop smoking during treatment, be sure to inform your doctor of this change.

Do not become pregnant while taking this medicine or for 1 month after stopping it. Women should inform their doctor if they wish to become pregnant or think they might be pregnant. There is a potential for serious side effects to an unborn child. Talk to your healthcare provider or pharmacist for more information. Do not breast-feed an infant while taking this medicine or for 2 weeks after stopping it.

Keep out of the reach of children.

Store at room temperature between 15 and 30 degrees C (59 and 86 degrees F). Throw away any unused medicine after the expiration date.