Phenylpropanolamine, an ingredient in this product, has been associated with an increased risk of hemorrhagic stroke (bleeding into the brain or into tissue surrounding the brain) in women. Men may also be at risk. Although the risk of hemorrhagic stroke is low, the U.S. Food and Drug Administration (FDA) recommends that consumers not use any products that contain phenylpropanolamine.
Drink plenty of extra fluids while taking this medication.
Do not crush or chew the tablets. Swallow them whole or break them in half where they are scored to make them easier to swallow if needed.
What is Guaifenex?
Guaifenesin is an expectorant. It is used to break up congestion and mucous to ease breathing. Guaifenesin thins mucous, increases lubrication of the respiratory tract (lungs, nose, and throat), and increases the removal of mucous.
Phenylpropanolamine and phenylephrine are decongestants. They constrict (shrink) blood vessels (veins and arteries), which reduces the swelling of mucous membranes in areas such as the nose and sinuses.
Guaifenex is used to treat the symptoms of the common cold and of infections of your sinuses, your lungs, and your throat.
Phenylpropanolamine, an ingredient in this product, has been associated with an increased risk of hemorrhagic stroke (bleeding into the brain or into tissue surrounding the brain) in women. Men may also be at risk. Although the risk of hemorrhagic stroke is low, the U.S. Food and Drug Administration (FDA) recommends that consumers not use any products that contain phenylpropanolamine.
Guaifenex may also be used for purposes other than those listed in this medication guide.
Who should not take Guaifenex?
Do not take Guaifenex if you have taken a monoamine oxidase inhibitor (MAOI) such as isocarboxazid (Marplan), phenelzine (Nardil), or tranylcypromine (Parnate) in the last 14 days. A dangerous drug interaction could occur, leading to serious side effects.
Before taking this medication, tell your doctor if you have
- high blood pressure or any other type of heart disease,
- diabetes,
- a peripheral vascular disorder (poor circulation),
- glaucoma or increased pressure in the eyes,
- an overactive thyroid, or
- difficulty urinating or an enlarged prostate.
You may not be able to take Guaifenex, or you may require a dosage adjustment or special monitoring during treatment if you have any of the conditions listed above.
Guaifenex is in the FDA pregnancy category C. This means that it is not known whether Guaifenex will harm an unborn baby. Do not take this medication without first talking to your doctor if you are pregnant.
Guaifenex passes into breast milk and may harm a nursing infant. Do not take this medication without first talking to your doctor if you are breast-feeding a baby.
If you are over 65 years of age, you may be more likely to experience side effects from Guaifenex. You may require a lower dose of this medication.
Guaifenex has not been approved for use by children younger than 6 years of age.
How should I take Guaifenex?
Take Guaifenex exactly as directed by your doctor. If you do not understand these directions, ask your pharmacist, nurse, or doctor to explain them to you.
Take Guaifenex with food if stomach upset occurs.
Do not crush or chew the tablets. Swallow them whole or break them in half where they are scored to make them easier to swallow if needed.
To ensure that you get a correct dose, measure the liquid form of Guaifenex with a special dose-measuring spoon or cup, not with a regular table spoon. If you do not have a dose-measuring device, ask your pharmacist where you can get one.
Store Guaifenex at room temperature away from moisture and heat.
What happens if I miss a dose?
Take the missed dose as soon as you remember. However, if it is almost time for the next dose, skip the missed dose and take only the next regularly scheduled dose. Do not take a double dose of this medication.
What happens if I overdose?
Seek emergency medical attention.
Symptoms of a Guaifenex overdose include vomiting, high blood pressure (headache, red face, blurred vision), an irregular heartbeat, and numbness of the fingers or toes.
What should I avoid?
Use caution when driving, operating machinery, or performing other hazardous activities. Guaifenex may cause dizziness. If you experience dizziness, avoid these activities.
What are the possible side effects of Guaifenex?
No serious side effects from Guaifenex are expected. Stop taking Guaifenex and seek emergency medical attention if you experience an allergic reaction (difficulty breathing; closing of your throat; swelling of your lips, tongue, or face; or hives).
Other, less serious side effects may be more likely to occur. Continue to take Guaifenex and talk to your doctor if you experience
- dizziness or headache;
- nervousness, restlessness, or insomnia;
- nausea or stomach upset; or
- difficulty urinating.
Side effects other than those listed here may also occur. Talk to your doctor about any side effect that seems unusual or that is especially bothersome.
See also: Side effects (in more detail)
What other drugs will affect Guaifenex?
Do not take Guaifenex if you have taken a monoamine oxidase inhibitor (MAOI) such as isocarboxazid (Marplan), phenelzine (Nardil), or tranylcypromine (Parnate) in the last 14 days. A dangerous drug interaction could occur, leading to serious side effects.
Heart medications such as methyldopa (Aldomet), reserpine (Serpalan, Serpasil), and guanethidine (Ismelin) may have decreased effects. Talk to your doctor before taking Guaifenex.
Do not take other over-the-counter cough, cold, allergy, diet, or sleep aids while taking Guaifenex without first talking to your doctor or pharmacist. Other medications may also contain guaifenesin, phenylephrine, phenylpropanolamine, or other similar drugs. You may accidentally take too much of these medicines.
Drugs other than those listed here may also interact with Guaifenex. Talk to your doctor and pharmacist before taking any prescription or over-the-counter medicines, including herbal products.
