What special precautions should I follow?  

Before taking guaifenesin,

• tell your doctor and pharmacist if you are allergic to guaifenesin or any other drugs.
• tell your doctor and pharmacist what prescription and nonprescription medications you are taking, including vitamins.
• tell your doctor if you have or have ever had high blood pressure, heart disease, thyroid disease, or diabetes.
• tell your doctor if you are pregnant, plan to become pregnant, or are breast-feeding. If you become pregnant while taking guaifenesin, call your doctor.

What should I do if I forget a dose?  

Take the missed dose as soon as you remember it. However, if it is almost time for the next dose, skip the missed dose and continue your regular dosing schedule. Do not take a double dose to make up for a missed one.