Not all medicines should be mixed as they can make the most terrible cocktails, so much so that they can cause adverse reactions, including some deadly ones. If your symptoms range from moderate to severe and you can't take it anymore, don't self-medicate, go or call a specialist.
Blood thinners.
If you were thinking of mixing Ibuprofen with anticoagulants such as warfarin, don't do it. The function of anticoagulants is to prevent blood clots from forming in the blood by making it more liquid, Ibuprofen does the same job to a lesser degree. Binding them together could cause a haemorrhage.
Antihypertensives.
Some of these medicines, enalapril for example, reduce the substances that enlarge vessels by increasing their fluidity. Ibuprofen causes the opposite, causing your blood pressure to swing wildly. If you suffer from blood pressure problems, don't even try it.
Antidepressants.
Antidepressants are very strong drugs with an incredible sedative capacity, and only available on prescription. When mixed with Ibuprofen, they can trigger cardiac arrhythmias and increase the likelihood of cranial haemorrhage.
Acetylsalicylic acid.
Yes, believe it or not, combining Ibuprofen with aspirin can be deadly. The effect of both prescriptions on the heart can lead users to develop serious heart problems. In addition, constant use of Ibuprofen decreases the effectiveness of aspirin.