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.

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 recommended adult dose of timolol depends on your circumstances and the condition being treated.

The starting dose for treatment of high blood pressure is usually 5 mg to 10 mg taken 2 times a day. Timolol is often used along with other medications to treat high blood pressure. The dose of medication is gradually increased by your doctor until the dose that is most effective for you, with the fewest side effects, is found. The maximum daily dose of timolol is 60 mg per day.

When treating angina, the starting dose is 5 mg taken 2 to 3 times daily. It may be gradually increased by your doctor to between 15 mg and 45 mg daily.

The usual dose to prevent another heart attack after the first one is 10 mg taken 2 times daily. Your doctor may suggest you start with a lower dose and then gradually increase.

The dose used to prevent migraine headaches is usually 10 mg taken 2 times a day, but it may range from 10 mg per day to 30 mg per day.

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 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

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.

• constipation
• decrease in sexual interest or ability
• diarrhea
• difficulty sleeping
• dizziness or lightheadedness
• drowsiness (slight)
• dry, sore eyes
• headache
• heartburn
• nausea
• nervousness
• nightmares or vivid dreams
• ringing in the ears
• spinning sensation
• stomach discomfort
• unusual tiredness or weakness
• vomiting

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
• cold hands and feet
• confusion (especially for seniors)
• decreased ability to concentrate
• difficulty urinating
• dizziness when getting up from a sitting or lying position
• fever and sore throat
• hallucinations (seeing or hearing things that aren't there)
• red, scaling or crusted skin
• signs of depression (e.g., poor concentration, changes in weight, changes in sleep, decreased interest in activities, thoughts of suicide)
• signs of heart problems (e.g., fast, irregular heartbeat or pulse, chest pain, sudden weight gain, difficulty breathing, leg swelling)
• signs of liver problems (e.g., nausea, vomiting, diarrhea, loss of appetite, weight loss, yellowing of the skin or whites of the eyes, dark urine, pale stools)
• skin rash
• slow heartbeat (especially less than 50 beats per minute)
• swelling of ankles, feet, or lower legs
• unusual bleeding or bruising
• worsening chest pain

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

• signs of a heart attack (e.g., chest pain or pressure, pain extending through shoulder and arm, nausea and vomiting, sweating)
• signs of stroke (e.g., sudden or severe headache; sudden loss of coordination; vision changes; sudden slurring of speech; or unexplained weakness, numbness, or pain in the arm or leg)
• 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.

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. If it is necessary to stop this medication, talk to your doctor about how to safely do so.

Breathing problems: Like other beta-adrenergic blockers, timolol can cause difficulty breathing for people who have asthma and certain other breathing problems. If you have breathing problems, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

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.

Kidney function: The kidneys are partially responsible for removing this medication from your body. Kidney disease or reduced kidney function may cause this medication to build up in the body, causing side effects. If you have reduced kidney function or kidney disease, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Myasthenia gravis: Myasthenia gravis is a condition that causes specific muscle weakness. Timolol can cause increase the symptoms of this illness. If you have with myasthenia gravis, should discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Thyroid disease: Timolol may hide the symptoms caused by an overproduction of thyroid hormone. If you have a history of thyroid problems, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Surgery: If you are going to have surgery, make sure you tell everyone involved in your care that you are taking this medication. It may be necessary to gradually reduce the dose of timolol, or stop the medication temporarily.

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. Talk to your doctor about whether you should continue breast-feeding.

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

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

• abiraterone
• acetylcholinesterase inhibitors (e.g., donepezil, galantamine, rivastigmine)
• alcohol
• aldesleukin
• aliskiren
• alpha agonists (e.g., clonidine, methyldopa)
• alpha/beta agonists (e.g., epinephrine, norepinephrine)
• alpha blockers (e.g., alfuzosin, doxazosin, tamsulosin)
• amifostine
• amiodarone
• amphetamines (e.g., dextroamphetamine, lisdexamfetamine)
• angiotensin-converting enzyme inhibitors (ACEIs; captopril, enalapril, ramipril)
• angiotensin receptor blockers (ARBs; e.g., candesartan, irbesartan, losartan)
• anti-malarial medications (e.g., hydroxychloroquine, primaquine)
• anti-psychotics (e.g., chlorpromazine, clozapine, haloperidol, olanzapine, quetiapine, risperidone)
• barbiturates (e.g., butalbital, phenobarbital)
• other beta-adrenergic blockers (e.g., atenolol, propranolol, sotalol)
• beta-2 agonists (e.g., salbutamol, formoterol, terbutaline)
• brimonidine
• bupropion
• calcium channel blockers (e.g., amlodipine, verapamil, diltiazem)
• celecoxib
• cinacalcet
• clomipramine
• conivaptan
• darifenacin
• diazoxide
• diabetes medications (e.g., acarbose, canagliflozin, , glyburide, insulin, linagliptin, lixisenatide, metformin, rosiglitazone)
• digoxin
• diphenhydramine
• dipyridamole
• disopyramide
• diuretics (water pills; e.g., furosemide, hydrochlorothiazide, triamterene)
• dronedarone
• duloxetine
• ergot alkaloids (e.g., dihydroergotamine, ergotamine,)
• fingolimod
• grass pollen allergen extract
• guanethidine
• HIV protease inhibitors (e.g., atazanavir, indinavir, ritonavir, saquinavir)
• lacosamide
• levodopa
• lanreotide
• lidocaine
• methadone
• methylphenidate
• minoxidil
• mirabegron
• monoamine oxidase (MAO) inhibitors (e.g., phenelzine, tranylcypromine) taken within the past 2 weeks
• nitrates (e.g., nitroglycerin, isosorbide dinitrate, isosorbide mononitrate)
• nonsteroidal anti-inflammatory medications (NSAIDs; e.g., ibuprofen, naproxen)
• obinutuzumab
• octreotide
• pasireotide
• pentoxifylline
• phosphodiesterase-5 inhibitors (e.g., sildenafil, tadalafil, vardenafil)
• pilocarpine
• pramipexole
• propafenone
• protein kinase inhibitors (e.g., ceritinib, imatinib, nilotinib, tofacitinib)
• quinine
• quinidine
• rifabutin
• rifampin
• selective serotonin reuptake inhibitors (SSRIs; e.g., citalopram, fluoxetine, paroxetine, sertraline)
• terbinafine
• theophyllines (e.g., aminophylline, oxtriphylline, theophylline)
• tizanidine
• yohimbine

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.