You can take both together. But I feel there is no use of taking these drugs together as both belongs to the same class i.e. both are H1 receptor antagonist. It is advisable to consider cetrizine over acrivastine, as cetrizine provides a more effective and long acting suppression on wheal and flare reactions. Moreover, cetrizine dose is normally once daily whereas dose of acrivastine is 3-4 times a day which prove expensive for the patients.

It is probably not a good idea, since theraflu typically contains another decongestant known as "phenylephrine." Combining the two decongestants could have harmful effects on blood pressure since they both constrict blood vessels.

I wouldn't take sudafed with theraflu. I would opt to go with either sudafed and Tylenol if a pain reliever therapy is preferred, or just taking theraflu.

Ive found phenylephrine to be a pretty effective decongestant, especially in the theraflu formulation

-3rd year Rx Student-

Benadryl®, or the generic diphenhydramine, is an antihistamine commonly used to treat allergy symptoms. It is also the primary ingredient in most over-the-counter sleep aids, because of its sedative side-effects.

If you've never taken diphenhydramine for sleep, chances are good that one will knock you out quickly. If you're still awake half-an-hour later, you can safely take a second dose, but no more.

Be aware that the sedative side-effects of diphenhydramine may last longer than expected, causing you to oversleep the next morning or feel groggy for several hours after waking.

If you have difficulty sleeping for more than two weeks, contact a physician for advice.

For more information about sleep hygiene, see the link.