Crying from fear or sadness (rather than happiness) involves more than just tears. The stress hormones adrenaline and cortisol make the muscles of your face and scalp scrunch up. This increases pressure on your skull, which can cause a tension headache.

A long crying session also works your facial muscles, and the lactic acid and other metabolic by-products of muscle fatigue will build up. These chemicals aren’t so easily flushed away, because the blood vessels around your face are also constricted by the muscle contractions. The resulting inflammation and nerve irritation turn into a dull aching pain.

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luis villazon
Luis VillazonQ&A expert

Luis trained as a zoologist, but now works as a science and technology educator. In his spare time he builds 3D-printed robots, in the hope that he will be spared when the revolution inevitably comes.