CareFirst Pharmacy is proud to bring custom-compounded theophylline in flavored, 4-way FlexDose tablets. If your veterinarian has prescribed theophylline for your pet, we are happy to provide an easy way to get just the right dose.

What is Theophylline?

Theophylline is a phosphodiesterase inhibitor drug and bronchodilator. It is mainly used in dogs and cats with respiratory diseases.

It directly relaxes muscles within the bronchi of the lungs and also in the pulmonary blood vessels. Theophylline can cause stimulation of the respiratory centers in the brain and has a mild diuretic effect, which may make it a helpful drug in managing congestive heart failure (CHF) in certain pets.

How could Theophylline help my pet?

Theophylline may be prescribed if your pet suffers from:

- Respiratory disease, such as:

  • Asthma
  • Chronic obstructive pulmonary disease (COPD)
  • Tracheal collapse (tracheomalacia)
  • Bronchitis
  • Pneumonia

- Heart Disease

  • Sick sinus syndrome (SSS)
  • Congestive heart failure (CHF)

In many conditions, the airways are constricted due to infection, inflammation or structural dysfunction. Theophylline helps to “open up” the airways, which can decrease coughing and improve lung function.

Side effects of Theophylline

Side effects to be aware of include:

- Nausea

- Vomiting

- Insomnia

- Increased appetite

- Increased thirst

- Increased urine production

- Diarrhea

- Increased stomach acid production

If you notice any of these symptoms, contact your veterinarian.

If your pet is pregnant, DO NOT give theophylline, as it has been shown to cause adverse effects on the fetus in animal studies.

Overdose or toxicity can cause seizures, abnormal heart rhythms, and elevated heart rate. If you think your pet has taken too much medicine or could have accidentally overdosed, contact pet poison control and/or your nearest veterinarian.

Drug Interactions

Many common medications can increase or decrease theophylline levels in the blood. Ones to be aware of include:

- Ketoconazole

- Furosemide (and other loop diuretics)

- Activated charcoal

- Beta-blockers

- Corticosteroids

- Fluoroquinolone antibiotics (ie. enrofloxacin, ciprofloxacin)

- Macrolide antibiotics (ie. Clindamycin)

- Propofol

- Benzodiazepines (ie. Valium)

- Ketamine

- Thyroid hormones (used in hypothyroid patients)

If your pet is taking any of these medications or may require surgery while taking theophylline, please let your veterinarian and pharmacist know before giving theophylline.

Use of theophylline in pets is considered “off-label”, please talk to your veterinarian in detail about risks and benefits of this medication.

CareFirst Caring for you and your pets

CareFirst Specialty Pharmacy has different sizes of compounded tablets available for pets large and small. Theophylline is available in 25mg minTabs and 100mg 4-way FlexDose tablets in chicken-flavored immediate release formulas.


Plumb’s Veterinary Drug Handbook. Theophylline. 8th Edition, January 1, 2015.

Related Products