Theophylline and Lithium Carbonate: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Theophylline
Lithium Carbonate
How we grade severity & evidence
Severity levels
- Contraindicated: These should generally not be used together.
- Major: Potentially serious — often needs a change or close monitoring.
- Moderate: Can be significant — usually manageable with monitoring.
- Minor: Usually limited clinical impact.
Evidence grades
- Established: Well documented — supported by controlled studies or strong clinical data.
- Probable: Good supporting evidence, though not definitively proven.
- Suspected: Some evidence suggests this interaction, but it is not well established.
- Possible: Limited or conflicting evidence; the interaction may occur.
- Theoretical: Predicted from the drugs' pharmacology; not yet confirmed in people.
Ratings come from the documented interaction literature and are reviewed by a pharmacist. They describe the documented risk of the combination, not what will necessarily happen to you — your dose, timing, and health picture all matter.
What happens
Decreased lithium effectiveness
Interaction Deep Dive
Concurrent use of theophylline and lithium has been reported to decrease serum lithium levels by 21% and shorten the lithium half-life by 22% compared to lithium alone in a study of healthy volunteers1. This appears to result from increased lithium clearance 2. Clinical cases of this interaction have also been reported 3.
Why it happens (mechanism)
Increased lithium clearance
Common questions
Can I take Theophylline and Lithium Carbonate together?
Decreased lithium effectiveness Always confirm with your pharmacist or prescriber before making any change.
How serious is the Theophylline and Lithium Carbonate interaction?
It is rated moderate. Can be significant — usually manageable with monitoring.
How quickly could this interaction happen?
The documented onset is "delayed". Effects tend to build up gradually over days to weeks.
How strong is the evidence for this interaction?
The evidence is graded "theoretical". Predicted from the drugs' pharmacology; not yet confirmed in people.
From our Q&A
Real reader questions about these medications, each personally answered by our pharmacist:
Questions for your pharmacist
- Does my dose of Theophylline or Lithium Carbonate need adjusting while I take them together?
- What symptoms should prompt me to call you or my prescriber right away?
- Does the timing of my doses matter for this combination?
- Is there anything you'd monitor while I'm on both?
References (3)
- Cook BL, Smith RE, Perry PJ, et al: Theophylline-lithium interaction. J Clin Psychiatry 1985; 46:7.
- Perry PJ, Calloway RA, Cook BL, et al: Theophylline precipitated alterations of lithium clearance. Acta Psychiatr Scand 1984; 69:528-537. PubMed
- Sierles FS & Ossowski MG: Concurrent use of theophylline and lithium in a patient with chronic obstructive lung disease and bipolar disorder. Am J Psychiatry 1982; 139:117-118. DOI
Keep reading about Theophylline
Keep reading about Lithium Carbonate
These medications also interact with supplements
Prescription drugs aren't the whole picture — herbal and dietary supplements can interact with them too. From the evidence-graded Natural Medicines database:
major · moderate · minor — check everything you take with our drug–supplement interaction checker.
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