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Discontinued Warning IconPlease Note: This Brand Name drug is no longer available in the US.
(Generic versions may still be available.)

Side Effects


The following adverse reactions have been observed, but there has not been enough systematic collection of data to support an estimate of their frequency. The most consistent adverse reactions are usually due to overdosage.

Gastrointestinal: nausea, vomiting, epigastric pain, hematemesis, diarrhea.

Central Nervous System: headaches, irritability, restlessness, insomnia, reflex hyperexcitability, muscle twitching, clonic and tonic generalized convulsions.

Cardiovascular: palpitation, tachycardia, extrasystoles, flushing, hypotension, circulatory failure, ventricular arrhythmias.

Respiratory: tachypnea.

Renal: potentiation of diuresis.

Other: alopecia, hyperglycemia, inappropriate ADH syndrome, rash.

Read the Slo-phyllin (theophylline, anhydrous) Side Effects Center for a complete guide to possible side effects


Drug-Drug Interactions: Toxic synergism with ephedrine has been documented and may occur with some other sympathomimetic bronchodilators. In addition, the following drug interactions have been demonstrated:

Theophylline with Drug Effect
Allopurinol (high dose) Increased serum theophylline levels
Cimetidine Increased serum theophylline levels
Ciprofloxacin  Increased serum theophylline levels
Erythromycin, Troleandomycin Increased serum theophylline levels
Lithium carbonate  Increased renal excretion of lithium
Oral contraceptives Increased serum theophylline levels
Propranolol Increased serum theophylline levels
Phenytoin Decreased theophylline and phenytoin serum levels
Rifampin Decreased serum theophylline levels

Last reviewed on RxList: 12/8/2004
This monograph has been modified to include the generic and brand name in many instances.

Side Effects

Report Problems to the Food and Drug Administration


You are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088.

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