Give your children effective relief from allergies plus nasal congestion and sinus pressure with grape-flavored Children’s BENADRYL® Allergy Plus Congestion. About a month or more ago, I started having this chest congestion where I am having a hard time coughing up phlegm. It comes and goes. Many times before going to sleep, I have to take some Benedryl for chest congestion and it seems to work until I wake in the morning and start my coughing again. Sometimes children put things up their nose that can become lodged and cause congestion and similar or associated symptoms, this is called foreign object nasal obstruction. Since Benadryl Allergy & Sinus Headache is taken when needed, you may not be on a dosing schedule. If you are taking the medication regularly, take the missed dose as soon as you remember. Skip the missed dose if it is almost time for your next scheduled dose. Do not take extra medicine to make up the missed dose. Over the counter medications, like other medications, should not be taken together without consulting your physician or pharmacist. So, Sudafed is nasal decongestant that contains pseudoehedrine as an active ingredient that shrinks blood vessels and decreases congestion while Benadryl can dry out secretions and can put you to sleep well. Those two products are working well for the same “cause” in different ways. There is no interaction between them and they are safe for use at the same time. Can you take Benadryl and Tylenol together Last reviewed by admin7 on September 5th, 2018. Benadryl is a Brand name for antihistamine drug that contains diphenhydramine as an active ingredient. Doctors give unbiased, trusted information on whether Benadryl can cause or treat Congestion: Dr. Villaplana on can you take robitussin chest and congestion be taken with benadryl: Yes no significant reaction. Worked for the most part I always used to take sudafed for congestion that helped but I feel adding the benadryl to it helps a little more and I can take it at night.