Istalol is a beta-blocker that also reduces pressure inside the eye.

Istalol ophthalmic solution is used to treat open-angle glaucoma and other causes of high pressure inside the eye.

Istalol may also be used for purposes not listed in this medication guide.

You should not use Istalol if you have asthma or severe COPD, or a serious heart condition (such as "sick sinus syndrome," 2nd or 3rd degree "AV block," severe heart failure, or very slow heartbeats).

Side effects may occur if timolol is absorbed into your bloodstream. Call your doctor right away if you have: chest pain, trouble breathing, slow heartbeats, muscle weakness, numbness or coldness in your hands or feet, unusual mood or behavior changes, or severe dizziness.

Do not allow the Istalol dropper to touch any surface, including the eyes or hands. If the dropper becomes contaminated it could cause an infection in your eye, which can lead to vision loss or serious damage to the eye.

Istalol can cause blurred vision. Be careful if you drive or do anything that requires you to be able to see clearly.

Use Istalol exactly as it was prescribed for you. Follow all directions on your prescription label and read all medication guides or instruction sheets. Your doctor may occasionally change your dose. Do not use this medicine in larger or smaller amounts or for longer than recommended.

Do not use this medicine while wearing contact lenses. Istalol may contain a preservative that can discolor soft contact lenses. Wait at least 15 minutes after using this medicine before putting in your contact lenses.

Wash your hands before using the eye drops.

To apply the Istalol eye drops:

• Tilt your head back slightly and pull down your lower eyelid to create a small pocket. Hold the dropper above the eye with the tip down. Look up and away from the dropper and squeeze out a drop.

• Close your eyes for 2 or 3 minutes with your head tipped down, without blinking or squinting. Gently press your finger to the inside corner of the eye for about 1 minute, to keep the liquid from draining into your tear duct.

• Use only the number of drops your doctor has prescribed. If you use more than one drop, wait about 5 minutes between drops.

• Wait at least 10 minutes before using any other eye drops your doctor has prescribed.

Do not touch the tip of the eye dropper or place it directly on your eye. A contaminated dropper can infect your eye, which could lead to serious vision problems.

Do not use the Istalol eye drops if the liquid has changed colors or has particles in it. Call your pharmacist for new medicine.

It may take a few weeks before your symptoms improve. Keep using the medication as directed and tell your doctor if your symptoms do not improve after 4 weeks of treatment.

If you need surgery, including eye surgery, tell the surgeon ahead of time that you are using Istalol. You may need to stop using the medicine for a short time.

You should not stop using Istalol suddenly. Follow your doctor's instructions about tapering your dose.

Store Istalol eye drops at room temperature away from moisture, heat, and light. Do not freeze. Keep the bottle tightly closed when not in use. Keep each single-use ampule inside its foil pouch until you are ready to use your dose.

A single-use ampule is for one use only. Throw it away after one use, even if there is still medicine left inside.

You should not use Istalol if you are allergic to timolol, or if you have:

• asthma or severe chronic obstructive pulmonary disease (COPD);

• certain serious heart conditions, especially "sick sinus syndrome" or 2nd or 3rd degree "AV block";

• severe heart failure; or

• slow heartbeats that have caused you to faint.

To make sure Istalol is safe for you, tell your doctor if you have ever had:

• heart disease, a stroke, a blood clot, or circulation problems;

• breathing problems;

• diabetes;

• a thyroid disorder;

• narrow-angle glaucoma;

• allergies; or

• a muscle disorder such as myasthenia gravis.

It is not known whether Istalol will harm an unborn baby. Tell your doctor if you are pregnant or plan to become pregnant.

Timolol can pass into breast milk and may harm a nursing baby. You should not breastfeed while using this medicine.

Istalol is not approved for use by anyone younger than 2 years old.

Use the medicine as soon as you can, but skip the missed dose if it is almost time for your next dose. Do not use two doses at one time.

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

Overdose symptoms may include dizziness, headache, slow heartbeats, and trouble breathing.

Istalol can cause blurred vision and may impair your reactions. Avoid driving or hazardous activity until you know how this medicine will affect you.

You may need to use other glaucoma medications in addition to Istalol. Do not use other eye medications unless your doctor tells you to.

Get emergency medical help if you have signs of an allergic reaction to Istalol: hives; difficult breathing; swelling of your face, lips, tongue, or throat.

Although the risk of serious side effects is low when timolol is used in the eyes, side effects can occur if the medicine is absorbed into your bloodstream. Call your doctor right away if you have:

• wheezing, chest pain, trouble breathing, slow heartbeats;

• a light-headed feeling, like you might pass out;

• muscle weakness;

• depressed mood, confusion, hallucinations, unusual thoughts or behavior; or

• numbness or cold feeling in your hands and feet.

Also call your doctor if you have:

• severe stinging or burning after using the eye drops:

• eye swelling, redness, severe discomfort, crusting or drainage (may be signs of infection); or

• blurred vision, tunnel vision, eye pain, or seeing halos around lights.

Common Istalol side effects may include:

• burning or stinging in your eye;

• dry eyes, itching;

• feeling like something is in your eye;

• red or puffy eyelids; or

• headache.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Sometimes it is not safe to use certain medications at the same time. Some drugs can affect your blood levels of other drugs you take, which may increase side effects or make the medications less effective.

Tell your doctor about all your current medicines and any you start or stop using, especially:

• any other beta-blocker eye medication - betaxolol, carteolol, levobunolol, or metipranolol;

• any other beta-blocker heart or blood pressure medicine - atenolol, bisoprolol, carvedilol, labetalol, metoprolol, nadolol, propranolol, sotalol, and others; or

• other heart or blood pressure medications - amiodarone, clonidine, digoxin, diltiazem, disopyramide, nicardipine, nifedipine, reserpine, verapamil, and others.

This list is not complete. Other drugs may interact with timolol ophthalmic, including prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible interactions are listed in this medication guide.