Headaches often result from poor lifestyle habits, a lack of proper sleep, or overworking. In most cases, a few additional hours of shut-eye every day are enough to alleviate such aches. However, sometimes, a headache could last longer and be a precursor to something much more severe, like diabetes, migraines, or, in a worst-case scenario, a brain tumor. Here are some alarming signs of a severe headache that should not be ignored. Nausea Nausea is often a symptom of a migraine—an unbearable, ear-splitting headache that can go on for hours. Migraines are incredibly common and often feature among the top ten causes of disability globally. Vomiting and a general, unrelenting sensation of nausea often come with, after, or before a bad migraine attack. So, if someone experiences an overwhelming feeling that they are about to throw up, it could be a sign of an impending migraine headache. Stiff neck A stiffened neck is sometimes followed or accompanied by a headache. While it may not be a cause for concern, one should see a doctor if the discomfort does not go away. Neck pain accompanied by a headache is one of the symptoms of meningitis, a bacteria- or virus-driven condition that affects the membranes covering the brain and spinal cord. These membranes swell and trigger a stiff neck and a bad headache. Meningitis is one of the hardest diseases to diagnose, as its symptoms are indicative of several other disorders. If one experiences a stiff neck and headache, the healthcare provider may examine the patient to verify whether they have meningitis before recommending a treatment. Changes in personality Some headaches are accompanied by other debilitating symptoms like weakness, confusion, a loss of basic coordination, and subtle changes in personality. These symptoms point toward the fact that the person has suffered a stroke. Personality changes involve increased irritability and a progressively reduced sense of direction or location. It may also involve an inability to walk in a straight line or speak without slurring. Fever Meningitis, migraines, strokes, and several other conditions could trigger a high fever. Often viral and bacterial conditions cause the body's immunity to take quickfire defense measures, which end up causing an increase in body temperature. If a person experiences a high fever, it could be a sign that a strong headache is about to follow soon after. Vision issues The eyes are closely connected to the head. So, a headache is often preceded by vision problems, such as being unable to see nearby or faraway objects clearly, night blindness, and blurry sight. Vision problems that appear along with headaches could also mean that one may have eye conditions like retinopathy that must be dealt with at the earliest.