BENYLIN Day & Night Tablets What it does Helps reduce temperature, relieve aches & pains, help clear congestion & so make it easier to nod off at night. How it works Diphenhydramine helps to relieve a runny nose, whilst pseudoephedrine causes the blood vessels in the nasal & sinus passages to contract & narrow, reducing congestion & the production of excess mucus. Paracetamol helps bring down a fever & provide relief from headaches or bodily aches & pains.