When This Medicine Should Not Be Used:
You should not use this medicine if you have had an allergic reaction to any xanthine bronchodilators such as theophylline, dyphylline, pentoxifylline, Difil G®, Dy-G®, Theo-Dur®, Trental®, or Uniphyl®. You should not use this medicine if you have had an allergic reaction to guaifenesin (Robitussin®).

How to Use This Medicine:
Tablet, Liquid, Capsule, Liquid Filled Capsule, Long Acting Tablet

• Take your medicine as directed. Your dose may need to be changed several times to find what works best for you. Your doctor might need to test your blood each time the dose is changed.
• You may take this medicine with or without food, but it might be best for you to take this medicine with a meal. Ask your doctor or pharmacist. It is important for you to take the medicine the same way every time. That means if you take your medicine with food, then you should always take it with food. If you take your medicine on an empty stomach, then you should always take it on an empty stomach.
• It is best to take your medicine at the same time every day.
• This medicine is available in several different forms. Sometimes the tablet or capsule has to be swallowed whole. Do not chew or crush any tablet or capsule that has to be swallowed whole. Sometimes the capsule can be opened and sprinkled on soft food. Ask your pharmacist how to take the specific kind of medicine that you are using. Make sure you understand all the directions, so you will get the right amount of medicine.
• Measure the oral liquid medicine with a marked measuring spoon, oral syringe, or medicine cup.

Drugs and Foods to Avoid:
Ask your doctor or pharmacist before using any other medicine, including over-the-counter medicines, vitamins, and herbal products.

• There are many other medicines that can interfere with xanthine medicines. This includes nonprescription (over-the-counter) medicines and herbal products. Make sure your doctor knows about all other medicines you are using.
• Other changes in your life might affect how much of this medicine you need. However, do not change your dose of medicine unless your doctor tells you to. Make sure your doctor knows if you have any of these changes:
  
  • Start or stop taking other medicines.
  • Eating different foods, especially if you want to limit protein or carbohydrates ("carbs").
  • Start or stop smoking, either you or someone you live with. This includes cigarettes or any other kind of tobacco, and marijuana.
• Make sure your doctor knows if you smoke.
• Tell your doctor if you eat beef that has been cooked over charcoal (such as on a grill) every day.
• Do not use St. John's wort while you are being treated with this medicine.

Warnings While Using This Medicine:

• Make sure your doctor knows if you are pregnant or breastfeeding, or if you have a stomach ulcer, seizures, glaucoma, or heart rhythm problems. Tell your doctor if you have liver disease, kidney disease, thyroid problems, or problems with your nervous system.
• Make sure your doctor knows about any other lung or heart problems you have, including cor pulmonale, pulmonary hypertension, congestive heart failure (CHF), or cystic fibrosis.
• Make sure your doctor knows if you are also using any kind of stimulant, such as ephedrine, ma huang, or Primatine®.
• Call your doctor if you start to run a fever or you get sick. An illness can change how much medicine you need. Your doctor will need to make sure you are not getting too much during the illness. Do not change your dose of medicine unless your doctor tells you to.
• Tell your doctor about any changes you have in other on-going health problems. This includes health problems that you see a different doctor for.
• If you start to have any serious side effects, do not take any more of this medicine until your doctor says it is okay.
• Your doctor will do lab tests at regular visits to check on the effects of this medicine. Keep all appointments. You might need to have the blood drawn at a specific time of the day.
• Make sure any doctor or dentist who treats you knows that you are using this medicine.
• Tell your doctor if you start to have symptoms in between the times you take your medicine.
• If you have a flare-up of breathing problems, do not use more medicine. Ask your doctor if you should have another medicine to use when you have a flare-up of breathing problems.
• If you feel that the medicine is not working as well, do not use more than your prescribed dose. Call your doctor for instructions.

Possible Side Effects While Using This Medicine:
Call your doctor right away if you notice any of these side effects:

• Nausea, repeated vomiting, trouble sleeping, fast heartbeat, on-going headache.
• Seizure.
• Uneven heartbeat.

If you notice these less serious side effects, talk with your doctor:

• Diarrhea.
• Headache.
• Increase in how much or how often you urinate.
• Trouble sleeping, restlessness, shakiness.

If you notice other side effects that you think are caused by this medicine, tell your doctor.
Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088