In the U.S.—

Another commonly used name is theophylline and glyceryl guaiacolate.

• Bronchodilator

Theophylline and guaifenesin (thee-OFF-i-lin and gwye-FEN-e-sin) combination is used to treat or prevent the symptoms of asthma or to treat chronic bronchitis and emphysema. This medicine relieves cough, wheezing, shortness of breath, and troubled breathing. It works by opening up the bronchial tubes (air passages) of the lungs and increasing the flow of air through them.

This medicine is available only with your doctor's prescription, in the following dosage forms:

Oral
• Capsules (U.S.)
• Elixir (U.S.)
• Oral solution (U.S.)
• Syrup (U.S.)

In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For theophylline and guaifenesin combination medicine, the following should be considered:

Allergies—Tell your doctor if you have ever had any unusual or allergic reaction to aminophylline, guaifenesin, oxtriphylline, or theophylline.

Diet—Make certain your health care professional knows if you are on any special diet, such as a high-protein, low-carbohydrate or low-protein, high-carbohydrate diet.

Pregnancy—Theophylline is used to treat asthma in pregnant women. Although there are no studies on birth defects in humans, problems have not been reported. However, some studies in animals have shown that theophylline can cause birth defects when given in doses many times the human dose.

Because your ability to clear theophylline from your body may decrease later in pregnancy, your doctor may want to take blood samples during your pregnancy to measure the amount of medicine in the blood. This will help your doctor decide whether the dose of this medicine should be changed.

Theophylline crosses the placenta. Use of this medicine during pregnancy may cause unwanted effects, such as fast heartbeat, irritability, jitteriness, or vomiting, in the newborn infant if the amount of medicine in your blood is too high.

Several groups of women taking guaifenesin during pregnancy have been studied. In one group, when guaifenesin was taken during the first 3 months of pregnancy, the babies had more inguinal hernias than expected. However, more birth defects than expected did not occur in the babies of other groups of women taking guaifenesin during pregnancy. Studies with guaifenesin have not been done in animals.

Breast-feeding—Theophylline passes into breast milk and may cause irritability in babies of mothers taking this medicine. Guaifenesin has not been reported to cause problems in nursing babies.

Children—The side effects of theophylline are more likely to occur in newborn infants, who are usually more sensitive to the effects of this medicine.

Although there is no specific information about the use of guaifenesin in children, it is not expected to cause different side effects or problems in children than it does in adults.

Older adults—Patients older than 60 years of age are likely to require a lower dose than younger adults. If the amount of theophylline is too high, side effects are more likely to occur. Your doctor may want to take blood samples to determine whether a dose change is needed.

Although there is no specific information about the use of guaifenesin in the elderly, it is not expected to cause different side effects or problems in older people than it does in younger adults.

Other medicines—Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are taking theophylline and guaifenesin combination medicine, it is especially important that your health care professional know if you are taking any of the following:

• Beta-adrenergic blocking agents including those used in the eyes (acebutolol [e.g., Sectral], atenolol [e.g., Tenormin], betaxolol [e.g., Betoptic, Kerlone], bisoprolol [e.g., Zebeta], carteolol [e.g., Cartrol], labetalol [e.g., Normodyne], levobunolol [e.g., Betagan], metipranolol [e.g., OptiPranolol], metoprolol [e.g., Lopressor], nadolol [e.g., Corgard], oxprenolol [e.g., Trasicor], penbutolol [e.g., Levatol], pindolol [e.g., Visken], propranolol [e.g., Inderal], sotalol [e.g., Sotacor], timolol [e.g., Blocadren, Timoptic])—These medicines may prevent theophylline from working properly

• Cimetidine (e.g., Tagamet) or
• Ciprofloxacin (e.g., Cipro) or
• Clarithromycin (e.g., Biaxin) or
• Enoxacin (e.g., Penetrex) or
• Erythromycin (e.g., E-Mycin) or
• Fluvoxamine (e.g., Luvox) or
• Mexiletine (e.g., Mexitil) or
• Pentoxifylline (e.g., Trental) or
• Tacrine (e.g., Cognex) or
• Thiabendazole or
• Ticlopidine (e.g., Ticlid) or
• Troleandomycin (e.g., TAO)—These medicines may increase the effects of theophylline

• Moricizine (e.g., Ethmozine) or
• Phenytoin (e.g., Dilantin) or
• Rifampin (e.g., Rifadin)—These medicines may decrease the effects of theophylline

• Smoking tobacco or marijuana—Starting or stopping smoking may change the effectiveness of this medicine

• Convulsions (seizures)—Theophylline may make this condition worse

• Heart failure or
• Liver disease or
• Underactive thyroid—The effects of theophylline may be increased

This medicine works best when taken with a glass of water on an empty stomach (either 30 minutes to 1 hour before meals or 2 hours after meals) since that way it will get into the blood sooner. However, in some cases your doctor may want you to take this medicine with meals or right after meals to lessen stomach upset. If you have any questions about how you should be taking this medicine, check with your doctor.

Take this medicine only as directed. Do not take more of it, do not take it more often, and do not take it for a longer time than your doctor ordered. To do so may increase the chance of serious side effects.

In order for this medicine to help your medical problem, it must be taken every day in regularly spaced doses as ordered by your doctor . This is necessary to keep a constant amount of this medicine in the blood. To help keep the amount constant, do not miss any doses.

Dosing—

When you are taking theophylline and guaifenesin combination, it is very important that you get the exact amount of medicine that you need. The dose of this medicine will be different for different patients. Your doctor will determine the proper dose of the theophylline and guaifenesin combination for you. Follow your doctor's orders or the directions on the label.

After you begin taking theophylline and guaifenesin combination, it is very important that your doctor check your blood level of theophylline at regular intervals to find out if your dose of theophylline and guaifenesin combination needs to be changed. Do not change your dose of theophylline and guaifenesin combination unless your doctor tells you to do so.

The number of capsules or teaspoonfuls of elixir, solution, or syrup that you take depends on the strength of the medicine.

Missed dose—

If you miss a dose of this medicine, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and go back to your regular dosing schedule. Do not double doses.

Storage—

To store this medicine:

• Keep out of the reach of children.
• Store away from heat and direct light.
• Do not store the capsule form of this medicine in the bathroom, near the kitchen sink, or in other damp places. Heat or moisture may cause the medicine to break down.
• Keep the liquid form of this medicine from freezing.
• Do not keep outdated medicine or medicine no longer needed. Be sure that any discarded medicine is out of the reach of children.

Your doctor should check your progress at regular visits, especially for the first few weeks after you begin taking this medicine. A blood test may be taken to help your doctor decide whether the dose of this medicine should be changed.

The theophylline in this medicine may add to the central nervous system stimulant effects of caffeine-containing foods or beverages such as chocolate, cocoa, tea, coffee, and cola drinks. Avoid eating or drinking large amounts of these foods or beverages while taking this medicine . If you have any questions about this, check with your doctor.

A change in your usual behavior or physical well-being may affect the way this medicine works in your body. Check with your doctor if you:

• have a fever of 102 °F or higher for at least 24 hours or higher than 100 °F for longer than 24 hours.
• start or stop smoking.
• start or stop taking another medicine.
• change your diet for a long time.

Before you have myocardial perfusion studies (a medical test that shows how well blood is flowing to your heart), tell the medical doctor in charge that you are taking this medicine. The results of the test may be affected by this medicine.

Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor as soon as possible if any of the following side effects occur:

• Less common or rare
  • Heartburn and/or vomiting 
  
  

• Symptoms of toxicity
  • Abdominal pain, continuing or severe;  confusion or change in behavior;  convulsions (seizures) ;  dark or bloody vomit;  diarrhea;  dizziness or lightheadedness;  fast and/or irregular heartbeat, continuing;  nervousness or restlessness, continuing;  trembling, continuing 
  
  

Other side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. However, check with your doctor if any of the following side effects continue or are bothersome:

• Less common
  • Fast heartbeat;  headache;  increased urination;  nausea;  nervousness;  trembling;  trouble in sleeping 
  
  

Other side effects not listed above may also occur in some patients. If you notice any other effects, check with your doctor.