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Theophylline ER

Theophylline ER by Teva Pharmaceuticals

Pharmacy Required

Theophylline ER 100mg and 200mg are currently on back order from the manufacturer. We recommend Theo-24.


Trade Names:


General Description:

Theophylline is used as a bronchodilator in dogs and cats with asthma or other respiratory conditions. It opens the lung's air passages by relaxing the muscles in the lungs and chest. It may also be used with other medications in the treatment of cardiac disease. Theophylline is sold by prescription as an extended release tablet.

What is this drug?
  • A bronchodilator; a member of the methylxanthine group of biochemicals
  • Given by mouth
Reasons for prescribing:
  • To treat heart failure, asthma, bronchitis and pulmonary edema in dogs and cats. It opens air passages in the lungs, increases the contraction strength of the diaphragm and clears mucus from the respiratory tract.
What dogs/cats should not take this medication?
  • Pregnant or nursing pets
  • Use with caution in patients with severe heart disease, cardiac arrhythmias, GI ulcers, hyperthyroid, glaucoma, high blood pressure, a history of seizures, liver or kidney disease
  • Use with caution in the very young, obese, debilitated or very old
  • If your pet has had an allergic reaction to theophylline, ethylenediamine or xanthines including theobromine and caffeine

Read and follow the label carefully.

Give on an empty stomach, 1 hour before or two hours after a meal.

Extended release tablets should be swallowed whole and not crushed or chewed to ensure that the medication is released slowly.

Give the exact amount prescribed and only as often as directed. It can be dangerous in high doses.

In dogs, this medication is usually given twice a day . In cats, it is given once a day (usually at bedtime in asthmatic cats).

Give this medication for as long as veterinarian directs. Do not skip doses or stop giving the medication without consulting your veterinarian.

Call ahead for refills.

Ideally, give the medication at the same time(s) daily.

Ensure your pet has plenty of fresh, clean drinking water.

What if a dose is missed?

If a dose is missed, give it as soon as you can. If it is time already for the next dose, skip the missed dose and go back to the normal schedule. Do not give two doses at the same time.

What to tell/ask veterinarian before giving medication?

Talk to your veterinarian about:

  • When will your pet need to be rechecked
  • What tests may need to be performed prior to and during treatment with this drug
  • What are the risks and benefits of using this drug

Tell your veterinarian about:

  • If your pet has experienced side-effects on other drugs/products
  • If your pet has experienced liver or kidney disease now or ever
  • If your pet has experienced any other medical problems or allergies now or ever
  • All medicines and supplements that you are giving your pet or plan to give your pet, including those you can get without a prescription. Your veterinarian may want to check that all of your pet's medicines can be given together.
  • If your pet is pregnant or nursing or if you plan to breed your pet
Storage and Warnings:

Refrigerate oral suspensions. Store all other forms in a tight, light resistant, childproof container in a cool, dry place at room temperature away from heat and direct sunlight. Protect from freezing.

Keep this and all medication out of reach of children and pets.

Call your physician immediately if you accidentally take this product.

Potential side effects:
  • Restlessness or caffeine-type jitters. A lower starting dose may minimize this effect
  • Mild stomach upset, racing heart with abnormal heart rhythm (not all patients)
  • Diuretic effect in some patients (increased thirst and urination)
  • Seizures and heart rhythm problems can occur with severe intoxication
  • There seems to be variations between brands. Some brands last too long, some not long enough. When the prescription is refilled, ensure that you are getting the correct brand and type as prescribed by your veterinarian.
  • If your pet shows any of these symptoms or you notice anything else unusual, contact your veterinarian
Can this drug be given with other drugs?
  • Yes, but possible interactions may occur with allopurinol, antacids, beta-blockers, cimetidine, ciprofloxacin, clindamycin, erythromycin, enrofloxacin, ephedrine, erythromycin, halothane, ketamine, lincomycin, lithium carbonate, pancuronium, phenobarbital, phenytoin and thiabendazole
  • If your pet experiences any unusual reactions when taking multiple medications, contact your veterinarian.

Contact your veterinarian immediately if pet receives more than the prescribed amount.

What else should I know?

Notify your veterinarian if your animal's condition does not improve or worsens despite this treatment.

As with all prescribed medicines, theophylline should only be given to the pet for which it was prescribed. It should be given only for the condition for which it was prescribed.

This is just a summary of information about theophylline. If you have any questions or concerns about theophylline or the condition it was prescribed for, contact your veterinarian.


Common Drug Name

Common Brand Names
Theo-24, Theolair 
Generic products are available.

Refrigerate oral suspensions and gummie chews, as directed. Store other forms at room temperature in a tight, light resistant, childproof container. Protect from extreme heat or freezing.

Theophylline is a bronchodilator, which relaxes the airways and makes breathing easier. It is used to treat asthma, heart failure, and certain lung conditions (e.g., pulmonary edema).

Dose and Administration
Always follow the dosage instructions provided by your veterinarian. If you have difficulty giving the medication, contact your veterinarian.

If you miss a dose, give it as soon as you remember. If it is almost time for the next dose, skip the one you missed and go back to the regular schedule. Do not give 2 doses at once. If you are uncertain whether to give a dose, contact your veterinarian.

This medication should only be given to the pet for whom it was prescribed.

Possible Side Effects
May cause loss of appetite, nausea, vomiting, diarrhea, or nervousness at the beginning of treatment. These side effects usually disappear after a short time. If they do not, or your pet has a rapid heartbeat, or an increase in appetite, drinking or urination, contact your veterinarian. 

May cause seizures at high doses. If so, contact your veterinarian immediately.
If your pet experiences an allergic reaction to the medication, signs may include facial swelling, hives, scratching, sudden onset of diarrhea, vomiting, shock, seizures, pale gums, cold limbs, or coma. If you observe any of these signs, contact your veterinarian immediately. 

Not for use in animals hypersensitive (allergic) to theophylline or xanthines, including theobromine and caffeine.

Use caution when using theophylline in very young or obese animals; animals who are older or debilitated; or those that have severe heart disease, irregular heart beats, stomach ulcers, hyperthyroidism, liver or kidney disease, hypoxia (lack of oxygen to the cells), high blood pressure, or a history of seizures. 

May cause or worsen abnormal heart rhythms.  

Do not allow the timed-release forms to be chewed or broken, as that would release large amounts of the medication at one time. 

Do not change brands without consulting a veterinarian as different brands may have different absorption rates in different animals. 

Do not use in pregnant or lactating animals (female animals nursing their young).

Consult with your veterinarian regarding the physical examinations and laboratory testing that may be recommended prior to and during treatment with theophylline.   

Drug, Food, and Test Interactions

Consult your veterinarian before using theophylline with phenobarbital, phenytoin, cimetidine, erythromycin, allopurinol, thiabendazole, clindamycin, lincomycin,  lithium carbonate,  pancuronium, beta-blockers (certain heart medications such as propranolol), ciprofloxacin, enrofloxacin (Baytril®), ephedrine, halothane (an inhalant anesthetic gas), and ketamine, since interactions may occur.  Always advise your veterinarian of any supplements you are giving your pet, including vitamins.

Signs of Toxicity/Overdose
May see seizures, fever, or rapid and irregular heart rates. 

An overdose can be fatal.

If you know or suspect your pet has had an overdose, or if you observe any of these signs in your pet, contact your veterinarian immediately.  

Keep this and all other medications out of the reach of children and pets.


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