Can Baby Aspirin Be Taken with Lithium?
Yes, low-dose aspirin (baby aspirin) can be safely taken with lithium, as aspirin does not significantly affect lithium levels or increase toxicity risk, unlike other NSAIDs.
Key Evidence Supporting Safety
The critical distinction is that aspirin behaves differently from other nonsteroidal anti-inflammatory drugs (NSAIDs) when combined with lithium:
- Aspirin does not increase plasma lithium levels, in contrast to other NSAIDs like indomethacin which can increase lithium levels by 40% 1
- In controlled studies, aspirin had no effect on steady-state plasma lithium concentrations and only minimally increased renal lithium elimination by 6% 1
- There is no convincing evidence that aspirin affects serum lithium levels to a clinically significant degree 2
The NSAID-Lithium Interaction (Why This Matters)
Understanding why other NSAIDs are problematic helps clarify why aspirin is safe:
- Most NSAIDs can increase serum lithium levels, diminish renal lithium clearance, and potentially induce lithium toxicity 2
- Indomethacin is the most potent offender, decreasing renal lithium elimination by 23% 1
- Ibuprofen and naproxen can significantly increase serum lithium levels with marked interindividual variation 2
- The mechanism involves prostaglandin suppression affecting renal lithium handling 1
Practical Recommendations
For patients on lithium requiring anti-inflammatory or antiplatelet therapy:
- Low-dose aspirin (81-100 mg daily) is preferable for patients on long-term lithium therapy who need antirheumatic or cardiovascular prophylaxis 1
- Aspirin may be used without the intensive monitoring required for other NSAIDs 1
- Standard lithium monitoring (checking levels periodically as part of routine care) remains appropriate 2
Important Caveats
While aspirin is safe regarding lithium interactions, monitor for:
- Standard aspirin contraindications: active bleeding, severe liver or kidney disease, aspirin allergy 3
- Gastric side effects, though low-dose aspirin has minimal gastric toxicity risk 4
- The combination does not require the frequent lithium level checks (every 4-5 days) needed when starting other NSAIDs 2
Clinical Context
If other NSAIDs must be used with lithium:
- Serum lithium levels must be checked every 4-5 days until the extent of drug interaction is assessed 2
- Lithium dosage reduction may be needed 2
- Diuretics (especially thiazides) and ACE inhibitors pose greater interaction risks than aspirin, with thiazides increasing lithium concentrations by 25-40% 5, 6
Bottom line: Aspirin stands apart from other NSAIDs in its safety profile with lithium and can be used without significant concern for lithium toxicity, making it the preferred choice when antiplatelet or anti-inflammatory therapy is needed in lithium-treated patients.