Can I take allegra (fexofenadine) d 24 hour with nyquil cold flu?

Allegra (fexofenadine) D . For treating allergies, Allegra (fexofenadine) d has been shown to be effective and safe. There is likely not much to be gained with adding nyquil except getting sleepy and a dry mouth. Try to avoid cough/cold products with multiple ingredients mixed with alcohol.
Avoid both. There is a small but real risk of respiratory depression (quitting breathing), or cardiac arrthymia due to a delay in the electrical signal that tells the heart to beat.

Related Questions

I am taking Allegra (fexofenadine) D non drowsy but I've got a bad cold can I take NyQuil cold and flu with it?

They are similar. NyQuil may make you drowsy. You neglect to itemize the details of your "bad cold". Are you taking any meds? The best approach can be determined only if the details are given. Read more...