脑膜炎是指包裹大脑和脊髓的保护薄膜急性炎症，而这些保护薄膜被统称为脑膜。脑膜发炎可由病毒、细菌或其他微生物的感染所引致，而在少数情况下或可由某种药物引发。脑膜炎由于其发炎位置接近大脑和脊髓，因此可以致命；所以此病为内科急诊的一种。

脑膜炎最常见的症状是头痛和颈部僵直，伴随发烧、精神错乱或意识改变、呕吐、无法忍受亮光（恐光症）或响亮的声音（声音恐惧症）。儿童通常只会出现非特异性的症状，如易怒和精神萎靡。如果出现皮疹，即表明该例脑膜发炎是由某特定诱因所引致；例如，由脑膜炎球菌引发的脑膜炎可伴随某种典型的皮疹。

Meningitis is an acute inflammation of the protective membranes covering the brain and spinal cord, known collectively as the meninges. The most common symptoms are fever, headache and neck stiffness. Other symptoms include confusion or altered consciousness, vomiting, and an inability to tolerate light or loud noises. Young children often exhibit only nonspecific symptoms, such as irritability, drowsiness, or poor feeding. If a rash is present, it may indicate a particular cause of meningitis; for instance, meningitis caused by meningococcal bacteria may be accompanied by a characteristic rash.