Like all medicines, Nurofen cold and flu tablets can cause side effects, although not everybody gets them. Side effects may be minimised by taking the lowest dose for the shortest time necessary to relieve the symptoms. You may suffer one of the known side effects of NSAIDs. If any of the side effects get serious, or if you notice any side effects not listed, tell your doctor or pharmacist. If you get any of the following at any time during your treatment, stop taking the medicine and seek immediate medical help: signs of intestinal bleeding such as bright red faeces (stools/motions), black tarry stools, vomiting blood, or dark particles that look like coffee grounds; signs of a serious allergic reaction such as difficulties in breathing or unexplained wheezing, dizziness or faster heartbeat, severe forms of skin reactions such as itchiness, skin rash with redness, peeling, flaking or blistering (e.g., Steven-Johnson syndrome), swelling of your face, tongue or throat; signs of kidney problems such as passing less or more urine, cloudy urine or blood in urine, pain in the back and/or swelling (particularly in the legs); signs of aseptic meningitis with neck stiffness and headache. For full details refer to the Patient Information Leaflet.