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PRECAUTIONS: Before using tetrahydrozoline, tell your doctor or pharmacist if you are allergic to it; or to preservatives (e.g., benzalkonium chloride); or if you have any other allergies.Before using this medication, tell your doctor or pharmacist your medical history, especially of: glaucoma, heart problems (e.g., heart attack, chest pain), high blood pressure, diabetes, eye infection/injury, overactive thyroid (hyperthyroidism).This drug may cause temporary blurred vision after you apply it. Do not drive, use machinery, or do any activity that requires clear vision until you are sure you can perform such activities safely.Caution is advised when using this product in children because they may be more sensitive to the effects of the product, especially eye irritation.During pregnancy, this medication should be used only when clearly needed. Discuss the risks and benefits with your doctor.It is not known whether this drug passes into breast milk. Consult your doctor before breast-feeding.

DRUG INTERACTIONS: If you are using this product under your doctor's direction, your doctor or pharmacist may already be aware of possible drug interactions and may be monitoring you for them. Do not start, stop, or change the dosage of any medicine before checking with your doctor or pharmacist first.Before using this medication, tell your doctor or pharmacist of all prescription and nonprescription/herbal products you may use, especially of: MAO inhibitors (e.g., furazolidone, linezolid, moclobemide, phenelzine, procarbazine, rasagiline, selegiline, isocarboxazid, tranylcypromine), guanethidine, tricyclic antidepressants (e.g., amitriptyline).This document does not contain all possible interactions. Therefore, before using this product, tell your doctor or pharmacist of all the products you use. Keep a list of all your medications with you, and share the list with your doctor and pharmacist.

Report Problems to the Food and Drug Administration   You are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088. Need help identifying pills and medications? Use the pill identifier tool on RxList.