Costco Pharmacy · Price Comparison 2026
Diphenhydramine at Costco Pharmacy: ~$11
Costco pharmacy prices are competitive, but membership is required. Script Unlock lets you compare Costco against competing local pharmacies. When independent pharmacies compete on Script Unlock, the same Diphenhydramine (Diphenhydramine Hydrochloride) is available from $2 — saving you $9 per fill.
Costco Pharmacy Price
~$11
typical cash price
Competing Pharmacies
From $2
when pharmacies compete
You Could Save
$9
vs Costco Pharmacy
Free · No account needed · Takes 30 seconds
Don't Pay Costco Pharmacy's $11 for Diphenhydramine
Pharmacies compete. You save $9. Takes 30 seconds.