Prescription pillsWhat is Theophylline?

Theophylline is a medication closely related to caffeine. It relaxes the muscles in the airways (bronchodilator), increases theĀ strength of the muscles involved with breathing, and improves how well mucus and debris are removed from the lungs.


  • Chronic bronchitis and other airway diseases in dogs
  • Feline asthma and bronchitis
  • Increases heart rate in cases of sick sinus syndrome and heart block
  • Decreases the risk for collapse in cases of vasovagal or tussive syncope (fainting)

Adverse Effects

[please contact CVCA should any of these symptoms be noted]

  • Caffeine like side effects (anxiety, restlessness, panting)
  • Decreased appetite, vomiting or diarrhea
  • Increased heart rate and risk for arrhythmias
  • Small increased risk for seizures in patients with preexisting epilepsy

Client Information

  • Best if given with food to avoid stomach upset
  • Comes in tablet form and liquid suspension
  • Very commonly used in conjunction with cardiac medications
  • Does not require any specific monitoring

Interactions with Other Drugs

  • Enrofloxacin, cimetidine, and clindamycin may increase blood levels increasing risk for side effects
  • Phenobarbital and ketoconazole may decrease blood levels lowering efficacy
  • The doctors at CVCA have taken this into account, however, please feel free to contact CVCA regarding any concurrent medications your pet may be prescribed

Standard Dosage Forms

Theophylline Tablets – 100mg, 200mg, 300mg

Theophylline Oral Liquid – 85mg/15ml


(Theophylline ER, Theo-dur, Slo-Bid)

Drug Handouts