Cold sore: Viruses or localised infections can cause the eye to redden â the problem usually starts in one eye, but can spread to both. The cold sore virus, which 90 per cent of us carry, can sometimes also infect the eye, causing inflammation.
Endorphins are chemicals, called peptides, that are made in the body. They have much of the same effect on a person as opium or morphine. As a result, they actually lower the feeling of pain in the body and can create a feeling of bliss or euphoria.
Endorphins are natural opium-like hormones that are produced by the pituitary gland and the hypothalamus of your body. Endorphins act on your brain's opiate receptors to block their ability to receive pain messages from the sensory nerves. This makes you less sensitive to pain.