the·​oph·​yl·​line thē-ˈä-fə-lən How to pronounce theophylline (audio)
: a feebly basic bitter crystalline compound C7H8N4O2 present in tea leaves that is isomeric with theobromine and is used in medicine especially as a bronchodilator

Example Sentences

Recent Examples on the Web The results didn’t mean theophylline, which is still in use, was a bad drug. Maggie Mckee, Discover Magazine, 1 Oct. 2014 With theophylline removed from his regimen, the patient flourished. Maggie Mckee, Discover Magazine, 1 Oct. 2014 Tea also contains two other types of methylxanthines, theophylline and theobromine, which are both considered to be muscle relaxants, Richardson says. Adele Jackson-gibson, Good Housekeeping, 1 Nov. 2022 And elderberry isn’t recommended for people taking diabetes medications, diuretics, corticosteroids, laxatives, the asthma drug theophylline, and those undergoing chemotherapy, Rothenberg adds. Erica Sweeney, Good Housekeeping, 27 Jan. 2021 When it’s broken down in the body, caffeine produces small amounts of the bronchodilator theophylline. Brad Rickman, Condé Nast Traveler, 17 Apr. 2018 The scientists found that amphetamine works with another ingredient, theophylline, a drug that is used for lung diseases such as asthma and bears a chemical resemblance to caffeine. Bradley J. Fikes,, 16 Aug. 2017 See More

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'theophylline.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History


International Scientific Vocabulary theo- (from New Latin thea tea) + phyll- + -ine entry 2

First Known Use

circa 1894, in the meaning defined above

Time Traveler
The first known use of theophylline was circa 1894

Dictionary Entries Near theophylline

Cite this Entry

“Theophylline.” Dictionary, Merriam-Webster, Accessed 6 Jun. 2023.

Medical Definition


the·​oph·​yl·​line thē-ˈäf-ə-lən How to pronounce theophylline (audio)
: a feebly basic bitter crystalline compound C7H8N4O2 that is present in small amounts in tea but is prepared chiefly by synthesis, that is isomeric with theobromine, and that is used in medicine often in the form of derivatives or in combination with other drugs especially as a bronchodilator to relieve or prevent symptoms of asthma and bronchospasm associated with chronic bronchitis and emphysema

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