Taking Promethazine With Codeine With NyQuil

Answer

It is generally not recommended to take promethazine with codeine and NyQuil together, for numerous reasons.

Both Drugs Contain Antihistamines

First and foremost, NyQuil contains the antihistamine doxylamine, which is similar to Benadryl in that it is classified as a sedating "first-generation" antihistamine.

Promethazine is also an antihistamine, with very similar effects to doxylamine, and may even be more sedating for some individuals.

Promethazine with doxylamine represents a double dose of sedating antihistamines and is considered a duplicate therapy. You will likely feel drowsy or more tired when taking these drugs together. In addition, you may experience other side effects including:

• Constipation
• Dizziness
• Difficulty with urination
• Dry mouth and eyes
• Changes in vision
• Fast heartbeat
• Confusion

Combining Codeine With Multiple Antihistamines Increases The Risk Of Side Effects

Not only will taking two different antihistamines likely cause some of the side effects mentioned in the section above, promethazine with codeine, of course, contains codeine. Adding on the doxylamine from NyQuil will further increase the risk of serious side effects, such as respiratory depression.

Final Words

Last but not least, both promethazine and codeine and NyQuil contain alcohol. While it isn't much alcohol, you still would be combining three drugs (i.e., doxylamine, promethazine, and ethanol) that are considered CNS (central nervous system) depressants.

The drugs should be avoided with one another unless your doctor has directed you otherwise.

Although the duration of action of these drugs can vary by individual, each lasts around 4 to 6 hours and should be separated by at least that amount of time.

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