If you purchase an over-the-counter expectorant, the active ingredient is almost certain to be guaifenesin. Guaifenesin thins secretions in the lungs and nasal passages, makes it easier to cough up phlegm and eases lung congestion. Guaifenesin has few side effects when taken at recommended dosages. However, manufacturers often combine guaifenesin with cough suppressants, decongestants and antihistamines as part of multisymptom cold medicines. These powerful multi-ingredient formulas can cause significant side effects. Take them with caution, and never take extra doses.
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For immediate-release guaifenesin expectorants, adults may take 200 to 400 milligrams every four hours or as needed, with a maximum of 2,400 milligrams per day. Tablets ordinarily contain 200 milligrams of guaifenesin each. For sustained-release formulations, the dosage is 600 to 1,200 milligrams every 12 hours, with each tablet containing 600 milligrams. With either formulation, do not take more than 2,400 milligrams per day.
Do not give adult expectorant formulations to children under 12 years of age, according to PubMed Health. Instead, administer guaifenesin expectorants specifically designed for children. Do not give expectorants to children under 4 years of age without physician approval. For immediate-release formulations, give children 4 to 6 years old 100 milligrams every four hours. Children ages 6 to 12 can have 100 to 200 milligrams every four hours. Each pill or sachet has 100 milligrams. Children should not have more than six doses in a 24-hour period. For sustained-release versions, follow package instructions and do not exceed 1,200 milligrams of medication per day. Children over age 12 can receive adult dosages.
You may be tempted to purchase medications to treat multiple cold symptoms, such as congestion, coughing and runny nose. Be cautious with these formulations, because antihistamines, decongestants and cough suppressants may cause a variety of side effects and drug interactions. Read labels carefully to determine the side-effect profile of specific mixtures. Decongestants such as pseudoephedrine and phenylephrine deserve special caution, as they can cause marked dizziness, insomnia and nausea. Purchase medications with the fewest active ingredients necessary to treat your symptoms.
If you experience signs of an allergic reaction while taking guaifenesin, discontinue taking it and seek medical attention. Guaifenesin may cause side effects such as dizziness, headache, rash or stomach upset, which are usually mild. Do not take guaifenesin while pregnant or breast-feeding without your doctor's approval. Prescription-only expectorants may combine guaifenesin with codeine or hydrocodone, opioid derivatives that suppress the cough reflex. Do not drink alcohol or drive while taking these medications, and take them exactly as prescribed.