Fludrex is used for relieving common cold & flu symptoms due to it's unique combination:- Paracetamol recommended dose to ease aches, pains, and lower body temperature. Pseudoephedrine HCI to clear a stuffy nose. Chlorpheniramine maleate is an antihistamine to relief Sinusitis and other allergic reactions. Caffeine to enhance the paracetamol effect and to gain more focus.