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guaifenesin and theophylline

Generic name: guaifenesin and theophylline [ gwye-FEN-e-sin-and-thee-OFF-il-in ]
Brand names: Ed-Bron G, Elixophyllin-GG, Asbron G, Slo-Phyllin GG, Quibron, ... show all 18 brands
Drug class: Antiasthmatic combinations

What is guaifenesin and theophylline?

Guaifenesin is an expectorant. It helps loosen congestion in your chest and throat, making it easier to cough out through your mouth.

Theophylline is a bronchodilator. Theophylline works in several ways: It relaxes muscles in your lungs and chest to increase airflow, decreases the sensitivity of your lungs to allergens and other substances that cause inflammation, and increases the contractions of your diaphragm so that more air is drawn into the lungs.

The combination of guaifenesin and theophylline is used to treat symptoms of asthma, bronchitis, and emphysema.

Guaifenesin and theophylline may also be used for other purposes not listed in this medication guide.

What is the most important information I should know about guaifenesin and theophylline?

Call your doctor right away if you experience nausea, vomiting, insomnia, restlessness, seizures, an increased heart rate, or a headache. These symptoms could be signs of too much theophylline in your blood.

Do not start or stop smoking without first talking to your doctor. Smoking changes the way your body uses theophylline, and you may need a dose adjustment.

Do not take more of this medicine than is prescribed without consulting your doctor. Seek medical attention if you are having increasingly difficult breathing.

What should I discuss with my healthcare provider before taking guaifenesin and theophylline?

You should not take this medication if you are allergic to guaifenesin or theophylline, or if you have:

  • a stomach ulcer; or

  • epilepsy or another seizure disorder.

Before taking guaifenesin and theophylline, tell your doctor if you are allergic to any drugs, or if you have:

  • heart disease or high blood pressure;

  • a heart rhythm disorder;

  • congestive heart failure;

  • fluid in your lungs;

  • a thyroid disorder;

  • fever;

  • liver disease; or

  • kidney disease.

If you have any of these conditions, you may need a dose adjustment or special tests to safely take this medication.

FDA pregnancy category C. This medication may be harmful to an unborn baby. Tell your doctor if you are pregnant or plan to become pregnant during treatment.

Guaifenesin and theophylline can pass into breast milk and may harm a nursing baby. Do not use this medication without telling your doctor if you are breast-feeding a baby.

Older adults may be more likely to have side effects from this medication.

How should I take guaifenesin and theophylline?

Take this medication exactly as prescribed by your doctor. Do not take it in larger amounts or for longer than recommended. Follow the directions on your prescription label.

Take this medicine with a full glass of water. Drink plenty of fluids to help loosen congestion and thin mucus.

Guaifenesin and theophylline can be taken with food to lessen stomach upset.

Take your doses at the same time every day to keep a constant level of guaifenesin and theophylline in your blood.

Measure liquid medicine with a special dose-measuring spoon or cup, not a regular table spoon. If you do not have a dose-measuring device, ask your pharmacist for one.

Do not switch brands or formulation (capsule, liquid) without your doctor's approval.

Store guaifenesin and theophylline at room temperature away from moisture and heat.

What happens if I miss a dose?

Take the missed dose as soon as you remember. If it is almost time for your next dose, wait until then to take the medicine and skip the missed dose. Do not take extra medicine to make up the missed dose.

What happens if I overdose?

Seek emergency medical attention if you think you have used too much of this medicine.

Overdose symptoms may include nausea, vomiting, headache, sleep problems, tremors, irritability, restlessness, fast heart rate, or seizure (convulsions).

What should I avoid while taking guaifenesin and theophylline?

This medication can cause side effects that may impair your thinking or reactions. Be careful if you drive or do anything that requires you to be awake and alert.

Avoid drinking alcohol while taking guaifenesin and theophylline. Alcohol can increase some of the side effects of this medication.

Do not start or stop smoking without first talking to your doctor. Smoking changes the way your body uses theophylline, and you may need a dose adjustment.

Avoid eating grilled or char-broiled foods. These foods may affect how theophylline works. Talk to your doctor before making changes in your diet.

Avoid caffeine (such as in coffee, tea, or cola), which can increase the side effects of theophylline.

Guaifenesin and theophylline side effects

Get emergency medical help if you have any of these signs of an allergic reaction: hives; difficulty breathing; swelling of your face, lips, tongue, or throat.

Call your doctor at once if you have a serious side effect such as:

  • seizure (convulsions);

  • fast or uneven heart rate; or

  • severe nausea or vomiting.

Less serious side effects may include:

  • mild skin rash;

  • slight nausea, decreased appetite, or weight loss;

  • restlessness, tremor, or insomnia; or

  • headache, lightheadedness, or dizziness.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

What other drugs will affect guaifenesin and theophylline?

Many drugs can interact with guaifenesin and theophylline. Below is just a partial list. Tell your doctor if you are using:

  • birth control pills;

  • ketoconazole (Nizoral);

  • an antibiotic such as ciprofloxacin (Cipro), clarithromycin (Biaxin), erythromycin (Ery-Tab, E.E.S, E-Mycin, others), levofloxacin (Levaquin), or rifampin (Rifadin, Rifamate, Rimactane);

  • a thyroid hormone such as levothyroxine (Synthroid, Levoxyl, Levothroid, others);

  • an interferon product such as Intron A, Alferon N, Infergen, Roferon-A, Betaseron, Avonex, Actimmune, and others;

  • a calcium channel blocker such as diltiazem (Cardizem, Dilacor XR, Tiazac), nifedipine (Procardia, Adalat), verapamil (Verelan, Calan, Isoptin), and others;

  • a beta-blocker such as atenolol (Tenormin), metoprolol (Lopressor, Toprol), propranolol (Inderal), timolol (Blocadren), and others;

  • asthma medication such as albuterol (Ventolin, Proventil, Volmax, others), salmeterol (Serevent), and others;

  • a diuretic (water pill); or

  • seizure medication such as phenytoin (Dilantin) or phenobarbital (Luminal, Solfoton).

There are many other medicines that can interact with guaifenesin and theophylline. Tell your doctor about all the prescription and over-the-counter medications you use. This includes vitamins, minerals, herbal products, and drugs prescribed by other doctors. Do not start using a new medication without telling your doctor. Keep a list with you of all the medicines you use and show this list to any doctor or other healthcare provider who treats you.

Where can I get more information?

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use this medication only for the indication prescribed.

Date modified: October 13, 2017
Last reviewed: December 15, 2010

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