Generic name: Terbutaline sulfate.

Other brand names: Brethaire, Bricanyl.

Brethine is a bronchodilator. It works by opening airways in the lungs and relaxing smooth-muscle tissue (such as in the lungs) to improve breathing. 

Quick Facts About Brethine


Used to prevent and relieve bronchial spasms in asthma, bronchitis, and emphysema.

Brethine Dosage

Take exactly as prescribed, do not take more often than recommended.

  • Usual adult dose: for Brethine — 5 milligrams at approximately 6-hour intervals, 3 times per day during waking hours. May be reduced to 2.5 milligrams if experiencing many side effects. Do not exceed 15 milligrams in a 24-hour period. For Brethaire—2 inhalations separated by 60-second interval, every 4 to 6 hours.
  • Usual child dose: for children under 12 years — not generally prescribed. For Brethine for children 12 to 15 years — 2.5 milligrams 3 times per day, not to exceed 7.5 milligrams in a 24-hour period. For Brethaire for children 12 years and older — 2 inhalations separated by 60-second interval, every 4 to 6 hours.
  • Missed dose: take as soon as possible, then take the remainder of medication for that day in equally spaced doses. Do not double doses.

Brethine Side Effects

Overdose symptoms:

same as the side effects. If you suspect an overdose, immediately seek medical attention.

More common side effects: chest discomfort, difficulty in breathing, dizziness, drowsiness, fast or flut-tery heartbeat, flushed feeling, headache, increased heart rate, nausea, nervousness, pain at injection site, rapid heartbeat, sweating, tremors, vomiting, weakness.

Less common Brethine side effects: anxiety, dry mouth, muscle cramps. Rare side effects: dry throat, throat irritation, unusual taste.


Inform your doctor before combining Brethine with:

antidepressants known as MAO inhibitors (Nardil or Parnate), beta-blockers (Inderal or Tenormin), other bronchodilators (Proventil or Ventolin), tricyclic antidepressants (Elavil or Tofranil).

No known food/other substance interactions.

Special Cautions

If pregnant or planning to become pregnant, inform your doctor immediately. Not known if Brethine appears in breast milk.

No special precautions apply to seniors.

Not generally prescribed for children under 12 years.

  • Should not use if sensitive to or had allergic reaction to this or similar medications such as Ventolin.
  • Inform your doctor before taking Brethine if you have: diabetes, heart disease, high blood pressure, irregular heart rate, an overactive thyroid gland, or seizures.

Note: provides accurate and independent information prescription pills, over-the-counter medicines and natural products. This material is provided for educational purposes only and is not intended for medical advice, diagnosis or treatment. If you have questions about  dosage, or Brethine side effects, please contact your healthcare provider.