Olopatadine belongs to the family of medications called antihistamines. It is used to relieve signs and symptoms of allergic conjunctivitis (an allergic reaction affecting the eyes), such as itchy eyes, red eyes, and swelling of the surface of the eye.

It works by blocking histamine, a substance released by the body during an allergic reaction. It also works by preventing the release of natural chemicals from cells in the body (mast cells) involved in an allergic reaction.

This medication may be available under multiple brand names and/or in several different forms. Any specific brand name of this medication may not be available in all of the forms or approved for all of the conditions discussed here. As well, some forms of this medication may not be used for all of the conditions discussed here.

Your doctor may have suggested this medication for conditions other than those listed in these drug information articles. If you have not discussed this with your doctor or are not sure why you are taking this medication, speak to your doctor. Do not stop taking this medication without consulting your doctor.

Do not give this medication to anyone else, even if they have the same symptoms as you do. It can be harmful for people to take this medication if their doctor has not prescribed it.

The usual recommended dose of olopatadine 0.1% is 1 to 2 drops in each affected eye twice daily.

The usual recommended dose of olopatadine 0.2% and olopatadine 0.7% is 1 drop in each affected eye once daily.

Before using the eye drops, wash your hands thoroughly. Follow your doctor or pharmacist's instructions on how to use the eye drops. Do not allow the eye dropper to touch any surface. This could contaminate the dropper and lead to an eye infection. Keep the bottle tightly closed when you are not using it.

If you use other eye drops, wait at least 5 minutes after using olopatadine eye drops before using the next eye drop. Use eye ointment last.

Many things can affect the dose of medication that a person needs, such as body weight, other medical conditions, and other medications. If your doctor has recommended a dose different from the ones listed here, do not change the way that you are taking the medication without consulting your doctor.

It is important to use this medication exactly as prescribed by your doctor. If you miss a dose, take it as soon as possible and continue with your regular schedule. If it is almost time for your next dose, skip the missed dose and continue with your regular dosing schedule. Do not take a double dose to make up for a missed one. If you are not sure what to do after missing a dose, contact your doctor or pharmacist for advice.

Store this medication at room temperature and keep it out of the reach of children.  Discard the bottle 4 weeks after opening it.

Each mL of clear, colourless liquid contains 1.11 mg of olopatadine hydrochloride equivalent to 1 mg of olopatadine.Nonmedicinal ingredients: benzalkonium chloride 0.10 mg (0.01%), sodium chloride, disodium hydrogen phosphate dodecahydrate, hydrochloric acid (to adjust pH), and water for injection.

Do not use this medication if you are allergic to olopatadine or any ingredients of the medication.

Many medications can cause side effects. A side effect is an unwanted response to a medication when it is taken in normal doses. Side effects can be mild or severe, temporary or permanent. The side effects listed below are not experienced by everyone who takes this medication. If you are concerned about side effects, discuss the risks and benefits of this medication with your doctor.

The following side effects have been reported by at less than 1% of people taking this medication. Many of these side effects can be managed, and some may go away on their own over time.

Contact your doctor if you experience these side effects and they are severe or bothersome. Your pharmacist may be able to advise you on managing side effects.

• blurred vision
• burning or stinging in the eyes
• changed sense of taste
• dizziness
• dry, itchy, irritated eyes
• dry nose or throat
• eyelid margin crusting
• fatigue
• headache
• increased tear production
• sensitivity to light

Although most of the side effects listed below don't happen very often, they could lead to serious problems if you do not seek medical attention.

Check with your doctor as soon as possible if any of the following side effects occur:

• eye discharge
• eye pain
• feeling as if something is trapped in the eye
• staining in your eye

Stop taking the medication and seek immediate medical attention if any of the following occur:

• symptoms of an allergic reaction, such as skin rash, hives, swelling, or itching

Some people may experience side effects other than those listed. Check with your doctor if you notice any symptom that worries you while you are taking this medication.

Before you begin using a medication, be sure to inform your doctor of any medical conditions or allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use this medication.

Blurred vision: Olopatadine eye drops my cause temporarily blurred vision.  Do not drive or operate machinery until your vision has cleared.

Contact lenses: The preservative in this medication can cause eye irritation and discolour contact lenses. If you wear contact lenses, remove them before inserting the drops, and wait 15 minutes before putting your lenses back in. If your eyes become red, take out your lenses and consult your eye doctor.

Pregnancy: This medication should not be used during pregnancy unless the benefits outweigh the risks. If you become pregnant while taking this medication, contact your doctor immediately.

Breast-feeding: Olopatadine may pass into breast milk. If you are a breast-feeding mother and are taking this medication, it may affect your baby. Talk to your doctor about whether you should continue breast-feeding.

Children: The safety and effectiveness of using olopatadine 0.1% eye drops has not been established for children under 3 years of age. The safety and effectiveness of using olopatadine 0.2% eye drops has not been established for children. The safety and effectiveness of olopatadine 0.7% eye drops has not been established for children under 2 years of age.

Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications that you are taking. Also tell them about any supplements you take. Since caffeine, alcohol, the nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them. Depending on your specific circumstances, your doctor may want you to:

• stop taking one of the medications,
• change one of the medications to another,
• change how you are taking one or both of the medications, or
• leave everything as is.

An interaction between two medications does not always mean that you must stop taking one of them. Speak to your doctor about how any drug interactions are being managed or should be managed.