Bacterial and Viral Causes

• Pinkeye symptoms, also known as "conjunctivitis," are commonly caused by both viral and bacterial infections. This can affect two eyes at once, or target only one side.
  
  In the case of a viral infection, the condition is often accompanied by excess mucus. Similarly, bacterial infections can produce a yellow or green liquid. Bacterial infections affecting the eyes may also produce symptoms in the throat or lungs.
  
  Regardless of the infection type, all pinkeye cases are contagious and can be found in children and adults.
  
  

Allerigic Causes

• Pinkeye symptoms can also be caused by allergies. This physical response results from the immune system reacting to an allergen, including dust and pollen. The body's immune system response creates cells that affect and irritate the lining of the eye.
  
  This allergy irritation commonly includes itching and inflammation. The membranes of the eye can also become swollen.
  
  

Irritation Causes

• Harmful irritation caused by foreign objects can also cause pinkeye symptoms. These irritants are often found in chemicals, such as those used in cleaning or sanitation.
  
  Signs of a foreign irritant include the discharge of mucus and reddening of the affected area. While these symptoms usually clear in a matter of days, severe irritation may require attention to remove the chemical irritant from the eye.