Active ingredient

• The active ingredient in Patanol is olopatadine, an antihistamine. Olopatadine reduces the release of histamines from the mast cells in the eye. Histamines cause the redness and itchiness of an allergic reaction.
  
  According to the product insert, each ml of Patanol contains 1.11 mg of olopatadine hydrochloride, which is the same as 1 mg of olopatadine.
  
  When olopatadine is used as an eye drop as prescribed, very little passes into the blood system. What little that does enter the blood system passes out of the body through the urine.
  
  

Preservatives

• The preservative in Patanol is benzalkonium chloride. It kills bacteria, some viruses, protozoa, yeasts and fungi. Soft contact lenses may absorb benzalkonium chloride, so if you use Patanol, wait at least 10 minutes before you put your contact lenses in.
  
  

Inactive Ingredients

• The inactive ingredients in Patanol are purified water, sodium chloride, dibasic sodium phosphate and hydrochloric acid/sodium hydroxide. They may be used, for example, to dilute the active ingredient or to maintain the pH balance of the medicine.
  
  

Warnings and Precautions

• Patanol is not to be used orally or injected. Although only a little bit of olopatadine, the active ingredient, passes into the blood system, we do not know if it can pass into the milk of nursing mothers. We also do not know if the olopatadine would hurt a developing fetus. If you are nursing or pregnant consult you doctor before using Patanol.
  
  Do not use Patanol if you are allergic to olopatadine hydrochloride or any of the other ingredients.