The pill is round and has a big x across the back of the pill. The A is on top of the 406
It might be an older pill.
More info at https://www.drugs.com/promethazine.html
Promethazine is used to treat allergy symptoms such as itching, runny nose, sneezing, itchy or watery eyes, hives, and itchy skin rashes.
Promethazine also prevents motion sickness, and treats nausea and vomiting or pain after surgery. It is also used as a sedative or sleep aid.
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