Tennis elbow is probably caused by an overstraining of the muscles.

The muscles that straighten the fingers and the wrist arise from a small projection of bone on the outer side of the elbow. In the case of tennis elbow, pain is concentrated around this area.

The pain may eventually radiate up the upper arm as well as down the outer side of the forearm.

The pain is caused by tiny breaks in the connective tissue that holds the muscles to the bone. The tissue is irritated and an inflammation sets in, causing swelling in the area. It often heals spontaneously but in a few cases the pain can last for more than five years.

Tennis elbow most frequently affects people in their 40s and upwards, and women are affected more frequently than men.

The symptoms of eosinophilia are those of the underlying condition. For example, eosinophilia due to asthma is marked by symptoms such as wheezing and breathlessness, whereas parasitic infections may lead to abdominal pain, diarrhoea, fever, or cough and rashes. Medicine reactions often give rise to skin rashes, and they often occur after taking a new drug. Rarer symptoms of eosinophilia can include weight loss, night sweats, lymph node enlargement, other skin rashes, and numbness and tingling due to nerve damage.