What causes Raynaud's phenomenon?
We don’t fully understand why some people develop Raynaud’s phenomenon and others don’t. For some reason the blood supply to the fingers and toes is reduced, especially in the cold.
The blood supply to the fingers and toes is controlled by nerves connected to the blood vessels. The nerves can reduce the blood supply in response to certain situations, one of which is exposure to severe cold. This prevents a loss of heat from the body. People with Raynaud’s phenomenon probably have an exaggerated response to cold and shut off the blood supply more quickly than normal.
Going out on a cold day or even reaching into the freezer to take out some food can bring on an attack of Raynaud's. Emotional changes, such as feeling anxious, can also cause an attack of Raynaud’s by triggering the nerves to shut down the blood supply.
Raynaud’s phenomenon can occur as a result of using vibrating machinery. This is called vibration white finger. Raynaud’s may also develop as a side-effect of certain drugs such as beta-blockers, which are used in the treatment of raised blood pressure and angina.