Diphenhydramine + LSD: Caution

Diphenhydramine+LSD

Caution

These combinations are not usually physically harmful, but may produce undesirable effects. Use caution.

Note: At 25-50mg, DPH may assist with side effects of the LSD such as nausea and anxiety. At higher dosages, the combination of a deliriant (DPH) and LSD is cautioned against. LSD is likely to increase the deliriant and negative effects of DPH, in addition to increasing the risk of severe injury and mental trauma. LSD and DPH at recreational dosages have additional cardiac concerns such as vasoconstriction, tachycardia, hypertension, which in combination may be exacerbated.

Substances in these categories

Diphenhydramine

LSD

Sources

Drugs of Abuse. In Encyclopedia of Toxicology (pp. 248–251). Elsevier. — Marraffa, J. M. (2014)
The Pharmacology of Lysergic Acid Diethylamide: A Review. CNS Neuroscience & Therapeutics, 14(4), 295–314. — Passie, T., Halpern, J. H., Stichtenoth, D. O., Emrich, H. M., & Hintzen, A. (2008)
Antiemetic Histamine H1 Receptor Blockers. In StatPearls. StatPearls Publishing. — Schaefer, T. S., Patel, P., & Zito, P. M. (2025)
Focus on Over-the-Counter Drugs’ Misuse: A Systematic Review on Antihistamines, Cough Medicines, and Decongestants. Frontiers in Psychiatry, 12, 657397. — Schifano, F., Chiappini, S., Miuli, A., Mosca, A., Santovito, M. C., Corkery, J. M., Guirguis, A., Pettorruso, M., Di Giannantonio, M., & Martinotti, G. (2021)
In Auricular Acupuncture & Addiction (pp. 93–135). Elsevier. — The drugs of misuse. (2009)
Diphenhydramine: Time to Move on? The Journal of Allergy and Clinical Immunology: In Practice, 10(12), 3124–3130. — Wolfson, A. R., Wong, D., Abrams, E. M., Waserman, S., & Sussman, G. L. (2022)

Interaction Matrix

Tap or hover on any cell to see the interaction. Click to view details.

✓+Synergy

✓Low Risk

↓Decrease

!Caution

⚠Unsafe

☠Dangerous


	!	!	↓	⚠	☠	↓	✓	!	⚠	⚠	?	✓+	!	↓	✓+	☠	✓+	!	!	?	!	✓+	!	!	✓+	✓	☠	?	↓	⚠
!		!	↓	!	☠	↓	✓	!	!	✓+	?	✓+	!	↓	✓+	☠	✓+	!	✓+	?	!	✓+	✓+	!	✓+	✓	✓+	✓+	↓	⚠
!	!		↓	⚠	☠	↓	✓	!	⚠	⚠	?	✓+	!	↓	✓+	?	✓+	☠	!	?	!	✓+	✓+	!	✓+	✓	☠	!	↓	⚠
↓	↓	↓		!	!	☠	✓	✓+	⚠	☠	☠	↓	↓	☠	☠	?	↓	⚠	!	?	↓	↓	☠	↓	!	☠	⚠	?	!	☠
⚠	!	⚠	!		☠	↓	!	!	!	⚠	!	!	⚠	!	!	✓	!	☠	!	?	!	!	!	⚠	✓+	!	⚠	⚠	✓	☠
☠	☠	☠	!	☠		↓	!	!	☠	☠	?	✓+	☠	↓	✓+	?	✓+	☠	☠	?	☠	✓+	☠	☠	✓+	✓	☠	?	☠	☠
↓	↓	↓	☠	↓	↓		↓	↓	↓	!	⚠	↓	↓	☠	!	?	↓	✓+	↓	?	↓	↓	!	↓	↓	☠	⚠	?	✓	☠
✓	✓	✓	✓	!	!	↓		✓	!	!	!	✓	!	✓	✓	?	✓	✓	!	!	✓	✓	✓	!	✓	✓	!	⚠	✓	✓
!	!	!	✓+	!	!	↓	✓		!	✓+	?	!	!	✓+	✓+	?	!	✓+	✓+	?	!	!	✓+	!	✓+	✓+	✓+	✓+	✓	✓+
⚠	!	⚠	⚠	!	☠	↓	!	!		⚠	!	!	⚠	!	!	↓	!	☠	!	?	!	!	!	⚠	✓+	☠	⚠	⚠	✓	☠
⚠	✓+	⚠	☠	⚠	☠	!	!	✓+	⚠		⚠	✓+	⚠	☠	✓+	☠	✓+	☠	☠	☠	✓+	✓+	⚠	⚠	✓+	☠	☠	⚠	☠	☠
?	?	?	☠	!	?	⚠	!	?	!	⚠		!	!	☠	☠	!	!	⚠	?	☠	!	!	☠	!	?	⚠	?	⚠	☠	☠
✓+	✓+	✓+	↓	!	✓+	↓	✓	!	!	✓+	!		✓+	↓	✓+	☠	✓+	✓+	✓+	✓+	✓+	✓+	✓+	✓+	✓+	✓	✓+	✓+	↓	⚠
!	!	!	↓	⚠	☠	↓	!	!	⚠	⚠	!	✓+		↓	✓+	☠	✓+	!	!	!	!	✓+	!	!	✓+	✓	⚠	!	↓	⚠
↓	↓	↓	☠	!	↓	☠	✓	✓+	!	☠	☠	↓	↓		☠	?	↓	✓+	!	!	↓	↓	☠	↓	!	☠	☠	☠	✓	☠
✓+	✓+	✓+	☠	!	✓+	!	✓	✓+	!	✓+	☠	✓+	✓+	☠		✓	✓+	!	✓+	?	✓+	✓+	✓+	✓+	✓+	☠	✓+	!	✓	☠
☠	☠	?	?	✓	?	?	?	?	↓	☠	!	☠	☠	?	✓		☠	?	☠	?	☠	☠	☠	☠	✓	?	?	?	✓	☠
✓+	✓+	✓+	↓	!	✓+	↓	✓	!	!	✓+	!	✓+	✓+	↓	✓+	☠		↓	✓+	!	✓+	✓+	✓+	✓+	✓+	✓	✓+	!	↓	⚠
!	!	☠	⚠	☠	☠	✓+	✓	✓+	☠	☠	⚠	✓+	!	✓+	!	?	↓		☠	?	!	✓+	⚠	!	✓	!	☠	?	☠	☠
!	✓+	!	!	!	☠	↓	!	✓+	!	☠	?	✓+	!	!	✓+	☠	✓+	☠		☠	✓+	✓+	!	!	✓+	✓	⚠	⚠	↓	☠
?	?	?	?	?	?	?	!	?	?	☠	☠	✓+	!	!	?	?	!	?	☠		?	✓+	?	?	?	!	?	⚠	?	☠
!	!	!	↓	!	☠	↓	✓	!	!	✓+	!	✓+	!	↓	✓+	☠	✓+	!	✓+	?		✓+	✓+	!	✓+	✓	✓+	!	↓	⚠
✓+	✓+	✓+	↓	!	✓+	↓	✓	!	!	✓+	!	✓+	✓+	↓	✓+	☠	✓+	✓+	✓+	✓+	✓+		✓+	✓+	✓+	✓	✓+	✓+	↓	⚠
!	✓+	✓+	☠	!	☠	!	✓	✓+	!	⚠	☠	✓+	!	☠	✓+	☠	✓+	⚠	!	?	✓+	✓+		!	✓+	☠	!	!	!	☠
!	!	!	↓	⚠	☠	↓	!	!	⚠	⚠	!	✓+	!	↓	✓+	☠	✓+	!	!	?	!	✓+	!		✓+	✓	✓+	☠	↓	⚠
✓+	✓+	✓+	!	✓+	✓+	↓	✓	✓+	✓+	✓+	?	✓+	✓+	!	✓+	✓	✓+	✓	✓+	?	✓+	✓+	✓+	✓+		!	✓+	!	✓	!
✓	✓	✓	☠	!	✓	☠	✓	✓+	☠	☠	⚠	✓	✓	☠	☠	?	✓	!	✓	!	✓	✓	☠	✓	!		!	☠	✓	☠
☠	✓+	☠	⚠	⚠	☠	⚠	!	✓+	⚠	☠	?	✓+	⚠	☠	✓+	?	✓+	☠	⚠	?	✓+	✓+	!	✓+	✓+	!		?	⚠	☠
?	✓+	!	?	⚠	?	?	⚠	✓+	⚠	⚠	⚠	✓+	!	☠	!	?	!	?	⚠	⚠	!	✓+	!	☠	!	☠	?		?	⚠
↓	↓	↓	!	✓	☠	✓	✓	✓	✓	☠	☠	↓	↓	✓	✓	✓	↓	☠	↓	?	↓	↓	!	↓	✓	✓	⚠	?		☠
⚠	⚠	⚠	☠	☠	☠	☠	✓	✓+	☠	☠	☠	⚠	⚠	☠	☠	☠	⚠	☠	☠	☠	⚠	⚠	☠	⚠	!	☠	☠	⚠	☠

Low Risk & Synergy

These drugs work together to cause an effect greater than the sum of its parts. They aren't likely to cause an adverse or undesirable reaction when used carefully.

Low Risk & No Synergy

Effects are additive. The combination is unlikely to cause any adverse or undesirable reaction beyond those that might ordinarily be expected from these drugs.

Low Risk & Decrease

One substance may reduce or counteract some of the effects of the other.

Caution

These combinations are not usually physically harmful, but may produce undesirable effects. Use caution.

Unsafe

There is considerable risk of physical harm when combining these substances. Use extreme caution.

Dangerous

These combinations are considered dangerous and should be avoided.

Unknown

The interactions between these substances are not well documented.