Why does scratching an itch make it worse?

The first instinct of most of us when it feels itching is to scratch it immediately. It is almost a reflex action upon which we don’t think twice. We scratch with every bit of insistence and it is one of the sweetest feelings in the world; until only when it gets worse. The itch persists and we scratch it again with more urgency, only to make it worse, sometimes even to the point of bleeding. The cycle continues and without a permanent relief for the person.
It is common knowledge that the itch becomes worse when we scratch on it, despite the momentary respite. What is the reason behind it? The recent studies shed a light on it.
The itching can be caused by a number of things, including allergic conditions and skin problems like eczema. Various diseases like Cancer are also accompanied by itching which sometime would go on to persist for life even after the disease is cured. A permanent itchy skin is one of the worst things to suffer and seriously affects the rhythm of daily life.
The temporary relief we feel when we scratch on the itch is because of the mild sensation of pain produced by it. When we scratch on the itch, the pain from it masks the itching sensation. When the neurons in spinal cord sends pain signals to the brain, it would respond by producing a hormone called Serotonin, which is known as ‘happy hormone’. Serotonin is a vital component in our body, which plays a seminal role in growth, bone metabolism and mood regulation.
The brain releases serotonin to control the pain since it does not want the pain to inhibit the body. But serotonin also activates the certain brain cells that intensify the itching sensation. These cells are called GRPR neurons. So, the every time we scratch, more serotonin is produced and it in turn further intensifies the itching sensation.
The fact was revealed in a study by the team of scientists from Washington University School of Medicine in St Louis, headed by Zhou-Feng Chen. They carried out some experiments in mice, half of which were genetically modified so that they lacked the genes for serotonin production. When the mice were injected with itch-inducing substance, the genetically modified ones showed fewer propensities for scratching than the normal ones. When they were injected with serotonin again, they showed same scratching tendency as the normal ones.
The study proves that serotonin plays a major part in the itch cycle. Suppression of serotonin or the receptors through which the GRPR neurons communicate with the hormone are the only ways to solve this problem. However, both will impact the body system adversely and are not ideal.

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