Mixing Lithium and Tylenol PM
Caution
Carries risk that is worth understanding before combining. Reduce doses and do not use alone.
Can you take Lithium with Tylenol PM?
Tylenol PM contains acetaminophen and diphenhydramine. The most concerning part is Lithium with Tylenol PM (Diphenhydramine): higher doses of diphenhydramine risk serotonin syndrome and heart-rhythm problems with lithium. Keep diphenhydramine to an ordinary 25–50 mg. MixSafe rates Lithium with Tylenol PM as "Caution" — carries risk that is worth understanding before combining. Reduce doses and do not use alone. Sources: the Drug Facts labels on DailyMed, the TripSit combination chart and MixSafe research. Educational information, not medical advice.
What is in it
- Tylenol PM
- Acetaminophen + Diphenhydramine.
Ingredient by ingredient
Lithium + Tylenol PM (Diphenhydramine)Caution
Higher doses of diphenhydramine risk serotonin syndrome and heart-rhythm problems with lithium. Keep diphenhydramine to an ordinary 25–50 mg.
There is a concern of serotonin syndrome at higher dosages of this combination. Caution is recommended in restricting diphenhydramine to medical dosages (25-50mg). Lithium and diphenhydramine both have concerns of QT prolongation which may be increased when taken in combination; risks increase due to a variety of factors such as the health of the user and drug dosages. Additionally, the combination may increase each drug's side effects, such as dizziness and loss of consciousness.
Source: TripSit drug combination chart
Lithium + Tylenol PM (Acetaminophen)Low risk, no synergy
Neither substance is expected to meaningfully change the other. Both still carry their own individual risks.
No specific interaction is documented. Acetaminophen's main risk is dose-dependent liver injury, so the thing to watch in any combination is total daily intake across all products (roughly 4g/24h) and anything else straining the liver.
Sources: Prescott LF. Paracetamol, alcohol and the liver. Br J Clin Pharmacol. 2000 · Acetaminophen: A Liver Killer or Thriller
- Tylenol PM Extra Strength, Drug Facts label. DailyMed. https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=ce58105b-f010-47af-8f31-6dd4ce4e9cba
Ingredient lists checked 2026-09-27. Formulas change and store brands differ, so the Drug Facts box on your own packet is the final word.
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