How does this medication work? What will it do for me?

Timolol belongs to the class of medications called beta-blockers. It is used for the treatment of high blood pressure. It is also used to prevent angina (chest pain), and to reduce the risk of having another heart attack after a heart attack has happened. Timolol is also used for the prevention of migraine headaches but is not useful for treatment of a headache once it has started.

Timolol blocks the action of chemicals that increase the heart's workload. Beta-blockers such as timolol lower the heart rate, blood pressure, and force of heart contraction. It is not known how beta-blockers work to prevent migraine headaches.

Your doctor may have suggested this medication for conditions other than the ones listed in these drug information articles. As well, some forms of this medication may not be used for all of the conditions discussed here. 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.

What form(s) does this medication come in?

5 mg
Each white, round, flat-faced with bevelled-edge tablet, scored and identified "APO" over "T5", contains timolol maleate 5 mg. Nonmedicinal ingredients: croscarmellose sodium, lactose monohydrate, magnesium stearate, and microcrystalline cellulose.

10 mg
Each light-blue, round, flat-faced with bevelled-edge tablet, scored and identified "APO" over "T10", contains timolol maleate 10 mg. Nonmedicinal ingredients: croscarmellose sodium, FD&C Blue No. 1 Aluminum Lake, FD&C Blue No. 2 Aluminum Lake, lactose monohydrate, magnesium stearate, and microcrystalline cellulose.

20 mg
Each light-blue, capsule-shaped tablet, scored and identified "APO T20", contains timolol maleate 20 mg. Nonmedicinal ingredients: croscarmellose sodium, FD&C Blue No. 1 Aluminum Lake, FD&C Blue No. 2 Aluminum Lake, lactose monohydrate, magnesium stearate, and microcrystalline cellulose.

How should I use this medication?

The recommended adult dose of timolol ranges from 5 mg twice a day to 30 mg twice a day depending on circumstances and the condition being treated. The starting dose for treatment of high blood pressure is usually 5 mg to 10 mg twice a day. Timolol is often used along with other medications for the treatment of high blood pressure. The dose of medication is gradually increased by your doctor until the best dose is found. Timolol may be taken with or without food. Do not stop taking this medication suddenly without speaking with your doctor first.

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 given here, do not change the way that you are taking the medication without consulting your doctor.

It is important to take 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, protect it from light and moisture, and keep it out of the reach of children.

Do not dispose of medications in wastewater (e.g. down the sink or in the toilet) or in household garbage. Ask your pharmacist how to dispose of medications that are no longer needed or have expired.

Who should NOT take this medication?

Do not take timolol if you:

  • are allergic to timolol or any ingredients of the medication
  • have congestive heart failure
  • have a severely enlarged heart
  • have a severely slow heart rate
  • have serious heart block (second- and third-degree AV block)
  • have cardiogenic shock
  • have allergic rhinitis, asthma or severe chronic obstructive respiratory diseases (e.g., emphysema, chronic bronchitis)
  • will soon be receiving anesthesia with medications such as ether

What side effects are possible with this 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 least 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.

  • anxiety
  • constipation
  • diarrhea
  • difficulty sleeping
  • dizziness or lightheadedness
  • drowsiness (slight)
  • dry, sore eyes
  • headache
  • itching of skin
  • nausea or vomiting
  • nervousness
  • stomach discomfort
  • unusual tiredness or weakness

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:

  • back or joint pain
  • chest pain
  • cold hands and feet
  • confusion (especially for seniors)
  • depression
  • dizziness when getting up from a sitting or lying position
  • fever and sore throat
  • hallucinations
  • irregular heartbeat
  • red, scaling or crusted skin
  • ringing in the ears
  • shortness of breath
  • skin rash
  • slow heartbeat (especially less than 50 beats per minute)
  • unusual bleeding or bruising
  • swelling of ankles, feet, or lower legs
  • yellow eyes or skin

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

  • symptoms of a severe allergic reaction, e.g.:
    • difficulty breathing
    • hives
    • swelling of the face or throat

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.

Are there any other precautions or warnings for 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.

Angina: If you are taking timolol to treat angina, do not stop the medication suddenly. There have been reports of severe worsening of angina, and of heart attack or abnormal heart rhythms occurring for people with angina who have done this. Talk to your doctor about how to safely stop the medication.

Breathing problems: People with asthma and certain other breathing problems should not take timolol.

Diabetes: The signs of low blood sugar may not be as noticeable when taking timolol. People who have diabetes who take insulin or other medications that work by reducing the levels of sugar in the blood should monitor their blood sugar carefully while taking this medication.

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: This medication passes into breast milk. If you are a breast-feeding mother and are taking timolol, it may affect your baby. Women should not breast-feed while taking this medication.

Children: The safety and effectiveness of using this medication have not been established for children.

What other drugs could interact with this medication?

There may be an interaction between timolol and any of the following:

  • alcohol
  • anti-arrhythmic medications (e.g., propafenone)
  • antidiabetes medications (e.g., insulin)
  • calcium channel blockers (e.g., verapamil, diltiazem)
  • clonidine
  • digoxin
  • dronedarone
  • epinephrine
  • ergot alkaloids (e.g., dihydroergotamine, ergotamine, methysergide)
  • guanethidine
  • medications for treating asthma (e.g., salbutamol)
  • medications that reduce blood pressure
  • methyldopa
  • monoamine oxidase (MAO) inhibitors (e.g., phenelzine, tranylcypromine) taken within the past 2 weeks
  • nonsteroidal anti-inflammatory medications (NSAIDs; e.g., ibuprofen, naproxen)
  • other beta-blockers (e.g., propranolol, metoprolol)
  • prazosin
  • quinidine
  • reserpine
  • rituximab
  • theophyllines (e.g., aminophylline, oxtriphylline, theophylline)
  • verapamil

If you are taking any of these medications, speak with your doctor or pharmacist. 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.

Medications other than those listed above may interact with this medication. Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications 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.