Generally, febrile patients should apply Merlin every 4-6 hours and not more than 4 times in 24 hours, because the main ingredient of Merlin is ibuprofen, which is a non-steroidal anti-inflammatory drug and has certain side effects on the human body after taking it. After taking Merlin, the more common side effects include causing gastrointestinal discomfort, such as stomach pain, acid reflux, nausea, vomiting, loss of appetite, and even peptic ulcers and bleeding in serious cases, and ibuprofen can also lead to liver and kidney function damage when taken in excess. If the interval is too short or the number of doses is too many, the above-mentioned adverse reactions will occur easily. Usually into the clinical are recommended for short-term moderate application, not overdose and overtime application. If the effect is not good after taking it, it may be that the patient is not sensitive to this type of drug, and can be replaced by another drug, such as acetaminophen, but the interval between each other should also be 4-6 hours. If patients do not have effective relief of fever symptoms even after 3 days of Merlin, they should go to the hospital promptly and ask the doctor for consultation and treatment, and should not increase the dose by themselves.