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Theo-24 Side Effects Center
Medical Editor: John P. Cunha, DO, FACOEP
Theo-24 (theophylline, anhydrous) is used to treat the symptoms of asthma, bronchitis and emphysema. It is a bronchodilator. Common side effects include mild nausea, loss of appetite, weight loss, restlessness, tremor, or insomnia, headache, lightheadedness, or dizziness.
Theo-24 is taken once daily, in doses ranging from 100 mg to 400 mg. Theo-24 may interact with carbamazepine, cimetidine, enoxacin, ephedrine or similar medications found in cold medicine or diet pills, erythromycin, fluvoxamine, propranolol, rifampin, St. John's wort, or thiabendazole. Tell your doctor all medications and supplements you use. During pregnancy, Theo-24 should be taken only if prescribed. It may be harmful to a fetus. This medication can pass into breast milk and may harm a nursing baby. Consult your doctor before breastfeeding.
Our Theo-24 (theophylline, anhydrous) Side Effects Drug Center provides a comprehensive view of available drug information on the potential side effects when taking this medication.
This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.
What is Patient Information in Detail?
Easy-to-read and understand detailed drug information and pill images for the patient or caregiver from Cerner Multum.
Theo-24 in Detail - Patient Information: Side Effects
Get emergency medical help if you have any of these signs of an allergic reaction: hives; difficulty breathing; swelling of your face, lips, tongue, or throat.
Stop using theophylline and call your doctor at once if you have any of these serious side effects:
- seizure (convulsions);
- worsening of your condition, or symptoms of new illness;
- severe or ongoing nausea and vomiting, headache, fast or uneven heart rate, and trouble sleeping (insomnia);
- coughing up blood or vomit that looks like coffee grounds;
- ongoing fever;
- feeling restless, irritable, nervous, or jittery.
- tremors; or
- urinating more than usual.
Less serious side effects may include:
- mild nausea, loss of appetite, weight loss;
- restlessness, tremor, or insomnia; or
- headache, lightheadedness, or dizziness.
This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088. You may report side effects to FDA at 1-800-FDA-1088.
Read the entire detailed patient monograph for Theo-24 (Theophylline Anhydrous Capsule) »
What is Prescribing information?
The FDA package insert formatted in easy-to-find categories for health professionals and clinicians.
Theo-24 FDA Prescribing Information: Side Effects
Adverse reactions associated with theophylline are generally mild when peak serum theophylline concentrations are < 20 mcg/ mL and mainly consist of transient caffeine-like adverse effects such as nausea, vomiting, headache, and insomnia. When peak serum theophylline concentrations exceed 20 mcg/mL, however, theophylline produces a wide range of adverse reactions including persistent vomiting, cardiac arrhythmias, and intractable seizures which can be lethal (see OVERDOSAGE). The transient caffeine-like adverse reactions occur in about 50% of patients when theophylline therapy is initiated at doses higher than recommended initial doses (e.g., > 300 mg/day in adults and > 12 mg/kg/day in children beyond 1 year of age). During the initiation of theophylline therapy, caffeine-like adverse effects may transiently alter patient behavior, especially in school age children, but this response rarely persists. Initiation of theophylline therapy at a low dose with subsequent slow titration to a predetermined age-related maximum dose will significantly reduce the frequency of these transient adverse effects (see DOSAGE AND ADMINISTRATION, Table V). In a small percentage of patients ( < 3% of children and < 10% of adults) the caffeine-like adverse effects persist during maintenance therapy, even at peak serum theophylline concentrations within the therapeutic range (i.e., 10-20 mcg/mL). Dosage reduction may alleviate the caffeine-like adverse effects in these patients, however, persistent adverse effects should result in a reevaluation of the need for continued theophylline therapy and the potential therapeutic benefit of alternative treatment.
Other adverse reactions that have been reported at serum theophylline concentrations < 20 mcg/mL include diarrhea, irritability, restlessness, fine skeletal muscle tremors, and transient diuresis. In patients with hypoxia secondary to COPD, multifocal atrial tachycardia and flutter have been reported at serum theophylline concentrations ≥ 15 mcg/mL. There have been a few isolated reports of seizures at serum theophylline concentrations < 20 mcg/mL in patients with an underlying neurological disease or in elderly patients. The occurrence of seizures in elderly patients with serum theophylline concentrations < 20 mcg/mL may be secondary to decreased protein binding resulting in a larger proportion of the total serum theophylline concentration in the pharmacologically active unbound form. The clinical characteristics of the seizures reported in patients with serum theophylline concentrations < 20 mcg/mL have generally been milder than seizures associated with excessive serum theophylline concentrations resulting from an overdose (i.e., they have generally been transient, often stopped without anticonvulsant therapy, and did not result in neurological residua).
Table IV. Manifestations of theophylline toxicity.*
|Percentage of patients reported with sign or symptom|
(Large Single Ingestion)
(Multiple Excessive Doses)
|Sign/Symptom|| Study 1
| Study 2
|Other supraventricular tachycardias||2||21||12||14|
|Ventricular premature beats||3||21||10||19|
|Atrial fibrillation or flutter||1||NR**||12||NR**|
|Multifocal atrial tachycardia||0||NR**||2||NR**|
|Ventricular arrhythmias with|
|* These data are derived from two studies
in patients with serum theophylline concentrations > 30 mcg/mL. In
the first study (Study #1-Shanon, Ann Intern Med 1993;119:1161-67), data
were prospectively collected from 249 consecutive cases of theophylline
toxicity referred to a regional poison center for consultation. In the
second study (Study #2-Sessler, Am J Med 1990;88:567-76), data were retrospectively
collected from 116 cases with serum theophylline concentrations > 30
mcg/mL among 6000 blood samples obtained for measurement of serum theophylline
concentrations in three emergency departments. Differences in the incidence
of manifestations of theophylline toxicity between the two studies may
reflect sample selection as a result of study design (e.g., in Study #1,
48% of the patients had acute intoxications versus only 10% in Study #2)
and different methods of reporting results.
** NR =Not reported in a comparable manner.
Read the entire FDA prescribing information for Theo-24 (Theophylline Anhydrous Capsule) »
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