Generic name: Theophylline.

Other brand names: Sustained-action — Aerolate Capsules, Constant-T, Elixophyllin SR, Quibron-T/SR, Respbid, Slo-bid Gyrocaps, Slo-Phyllin Gyrocaps, Susaire, Theobid Duracaps, Theobid Jr. Duracaps, Theoclear L.A., Theocron, Theo-Dur Sprinkle, Theolair-SR, Theophylline S.R., Theo-Sav, Tneospan-SR, Theo-24, Theovent, T-Phyl, Uniphyl. Extended-release — Accubron, Aquaphyliin, Asmalix, Bronkodyl, Elixomin, Elixophyllin, Lanophyllin, Quibron-T, Slo-Phyllin, Theoclear, Theolair, Theostat.

Theo-Dur is a xanthine bronchodilator. It works by relaxing the smooth muscle of the bronchial airways, thereby opening air passages to the lungs.

Quick Facts About Theo-DurTheo-Dur


Used to prevent or relieve asthma, chronic bronchitis, and emphysema. Active ingredient is theophylline, a chemical cousin of caffeine.

Theo-Dur Dosage

Take exactly as prescribed. Comes in extended-release and sustained-action forms. Swallow extended-release form whole; never crush or swallow, and may take with or without food. Must take sustained-action (Theo-Dur Sprinkle) 1 hour before or 2 hours after a meal. May swallow capsule whole or empty contents onto a spoonful of soft (not hot) food, not crushing or chewing contents. Follow with glass of cool water or juice. Only doctor or pharmacist should change brands.

  • Usual adult dose: extended-release—initially 1 Theo-Dur 200-milligram tablet every 12 hours. Doctor will gradually increase up to 900 milligrams per day. Theo-Dur Sprinkle — no more than 200 milligrams every 12 hours. Doctor may increase up to 900 milligrams per day. Dose may be divided into 3 doses.
  • Usual child dose: extended-release — 55 to 76 pounds — 500 milligrams. Extended-release — 77 through 154 pounds — 600 milligrams. Theo-Dur Sprinkle — children ages 6 to 8 — 24 milligrams per 2,2 pounds of body weight. Theo-Dur Sprinkle — children ages 9 to 11 — 20 milligrams per 2.2 pounds of body weight. Theo-Dur Sprinkle — children ages 12 to 15 — 18 milligrams per 2.2 pounds of body weight. For children under 55 pounds — liquid preparation recommended before switching to tablet or sprinkle form.
  • Missed dose: take as soon as possible, unless almost time for next dose. In that case, do not take missed dose, go back to regular schedule. Do not double doses.

Theo-Dur Side Effects

Overdose symptoms:

flu shot or influenza may cause usual dose to act like an overdose. Most of side effects are caused by slight overdose. Mild overdose symptoms: nausea and restlessness. Larger overdose may cause serious heartbeat irregularities, convulsions, or death. If you suspect an overdose, immediately seek medical attention.

More common side effects: restlessness, nausea. Other side effects: convulsions, diarrhea, disturbances of heart rhythm, excitability, flushing, frequent urination, hair loss, headache, heart palpitations, high blood sugar, irritability, low blood pressure, muscle twitching, nausea, rapid breathing, rapid heartbeat, rash, restlessness, sleeplessness, stomach pain, vomiting, vomiting blood. May also cause or worsen heartbeat abnormalities. Contact your doctor if you notice significant change in your heart rate or rhythm.

No known less common or rare Theo-Dur side effects.


Inform your doctor before combining Theo-Dur with:

allopurinol (Lopurin or Zyloprim); cimetidine (Tagamet); ciprofloxacin (Cipro); ephedrine in medications (Primatene, Tedral, or Rynatuss); erythromycin (E.E.S., ERYC, or Erythrocin); lithium carbonate (Eskalith or Lithobid); oral contraceptives; phenytoin (Dilantin); propranolol (Inderal); rifampin (Rifadin, Rifamate, or Rimactane); troleandomycin (Tao).

Avoid large amounts of caffeine-containing beverages.

Special Cautions

If pregnant or planning to become pregnant, inform your doctor immediately. Appears in breast milk, causing irritability and other harm to nursing baby.

Seniors should use with precaution, especially males over 55 with chronic lung disease.

Follow doctor’s instructions carefully for children over 10 years.

  • Do not take if sensitive to or allergic to Theo-Dur, or if you have an active peptic ulcer.
  • If epileptic, make sure your antiseizure medication is the correct dose before taking Theo-Dur.
  • Use cautiously if you have or had: sustained a high fever, heart disease or liver failure, high blood pressure, low blood oxygen, alcoholism, or history stomach ulcers.

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 Theo-Dur side effects, please contact your healthcare provider