Skip to Content

Timolol Side Effects

In Summary

More frequently reported side effects include: cardiac failure and weakness. See below for a comprehensive list of adverse effects.

For the Consumer

Applies to timolol: oral tablet

As well as its needed effects, timolol may cause unwanted side effects that require medical attention.

Major Side Effects

If any of the following side effects occur while taking timolol, check with your doctor immediately:

More common:
  • Chest pain or discomfort
  • lightheadedness, dizziness, or fainting
  • shortness of breath
  • slow or irregular heartbeat
  • unusual tiredness
Less common:
  • Difficult or labored breathing
  • fast heartbeat
  • tightness in chest
  • wheezing
  • Noisy breathing
  • small clicking, bubbling, or rattling sounds in the lung when listening with a stethoscope
  • swelling of hands, ankles, feet, or lower legs

If any of the following symptoms of overdose occur while taking timolol, get emergency help immediately:

Symptoms of overdose:
  • Blurred vision
  • continuing ringing or buzzing or other unexplained noise in ears
  • headache
  • hearing loss
  • nervousness
  • pounding in the ears
  • sweating

Minor Side Effects

Some timolol side effects may not need any medical attention. As your body gets used to the medicine these side effects may disappear. Your health care professional may be able to help you prevent or reduce these side effects, but do check with them if any of the following side effects continue, or if you are concerned about them:

Less common:
  • Itching skin
  • red, sore eyes
  • Acid or sour stomach
  • belching
  • burning, crawling, itching, numbness, prickling, "pins and needles", or tingling feelings
  • decreased interest in sexual intercourse
  • feeling of constant movement of self or surroundings
  • heartburn
  • inability to have or keep an erection
  • indigestion
  • lack or loss of strength
  • loss in sexual ability, desire, drive, or performance
  • nausea
  • sensation of spinning
  • stomach discomfort, upset, or pain

For Healthcare Professionals

Applies to timolol: compounding powder, oral tablet


Cardiovascular side effects are the most common. Sinus bradycardia is reported in 9% of patients. Atrioventricular conduction disturbances, hypotension, and exacerbation of congestive heart failure are reported in less than 1% of patients.[Ref]


Alternative therapy should be considered in patients with reactive airways disease. Cases of fatal respiratory arrest are reported in patients with asthma, even after topically administered timolol.[Ref]

Respiratory problems associated with timolol, like with other beta antagonists, include bronchial constriction in susceptible patients. Dyspnea is reported in 6% of patients.[Ref]

Nervous system

A case of amaurosis fugax is associated with timolol. However, the patient involved had underlying cerebrovascular disease, autonomic dysfunction, and an arrhythmia.[Ref]

Nervous system side effects include fatigue in 6%, headache in 4%, and dizziness in 6% of treated patients. Cases of visual hallucinations, insomnia and depression have been reported rarely. Timolol may worsen myasthenia gravis.[Ref]


Endocrinologic side effects of timolol include masking the signs and symptoms and blunting the normal physiologic response to hypoglycemia. Timolol may cause an increase in serum triglycerides, LDL cholesterol, and VLDL cholesterol, and a decrease in HDL cholesterol.[Ref]

Alternative therapy should be considered in patients with diabetes mellitus who are prone to hypoglycemia.[Ref]


Psychiatric side effects, such as confusion, depression (including acute suicidal ideation), vivid and frightening dreams, and visual hallucinations are reported in rare cases.[Ref]

Sexual dysfunction is reported from questionnaires, although the questions may have biased the data since the responses were not spontaneous.[Ref]


Gastrointestinal complaints of general abdominal pain, nausea, constipation, or diarrhea are reported in 1% to 5% of patients.[Ref]


Dermatologic side effects are unusual. Rare cases of generalized psoriasis and hyperpigmented nailbeds are reported.[Ref]


Genitourinary complaints of impotence and decreased libido are rare.[Ref]


Musculoskeletal side effects are rare. Timolol may worsen myasthenia gravis.[Ref]


General side effects including decreased exercise tolerance, extremity pain, weight loss and fever have been reported.[Ref]


Hypersensitivity reactions including anaphylaxis have been reported in clinical experience with timolol.[Ref]


1. "Product Information. Blocadren (timolol)." Merck & Co, Inc, West Point, PA.

2. Fraunfelder FT, Meyer SM "Sexual dysfunction secondary to topical ophthalmic timolol." JAMA 253 (1985): 3092-3

3. Clark BG, Vestal RE "Adverse drug reactions in the elderly: case studies." Geriatrics 39 (1984): 53-66

4. Shiuey Y, Eisenberg MJ "Cardiovascular effects of commonly used ophthalmic medications." Clin Cardiol 19 (1996): 5-8

5. Yates D "Syncope and visual hallucinations, apparently from timolol." JAMA 244 (1980): 768-9

6. Edeki TI, He H, Wood AJ "Pharmacogenetic explanation for excessive B-blockade following timolol eye drops." JAMA 274 (1995): 1611-3

7. Mashford ML, Coventry D, Hecker R, et al. "Adverse Drug Reactions Advisory Committee: ADRAC report for 1980." Med J Aust 1 (1982): 416-9

8. Uusitalo RJ, Palkama A "Efficacy and safety of timolol pilocarpine combination drops in glaucoma patients." Acta Ophthalmol (Copenh) 72 (1994): 496-504

9. Treseder AS, Thomas TP "Sinus arrest due to timolol eye drops." Br J Clin Pract 40 (1986): 256-8

10. Frishman WH, Fuksbrumer MS, Tannenbaum M "Topical ophthalmic beta-adrenergic blockade for the treatment of glaucoma and ocular hypertension." J Clin Pharmacol 34 (1994): 795-803

11. Altus P "Timolol-induced congestive heart failure." South Med J 74 (1981): 88

12. Dunn FG, Frohlich ED "Pharmacokinetics, mechanisms of action, indications, and adverse effects of timolol maleate, a nonselective beta-adrenoreceptor blocking agent." Pharmacotherapy 1 (1981): 188-200

13. Odonoghue E "Beta blockers and the elderly with glaucoma: are we adding insult to injury?" Br J Ophthalmol 79 (1995): 794-6

14. Prince DS, Carliner NH "Respiratory arrest following first dose of timolol ophthalmic solution." Chest 84 (1983): 640-1

15. Kaufman HS "Timolol-induced vasomotor rhinitis: a new latrogenic syndrome." Arch Ophthalmol 104 (1986): 967, 970

16. Hayes LP, Stewart CJ, Kim I, Mohr JA "Timolol side effects and inadvertant overdosing." J Am Geriatr Soc 37 (1989): 261-2

17. Odeh M, Oliven A, Bassan H "Timolol eyedrop-induced fatal bronchospasm in an asthmatic patient." J Fam Pract 32 (1991): 97-8

18. Dunn TL, Gerber MJ, Shen AS, Fernandez E, Iseman MD, Cherniak RM "The effect of topical ophthalmic instillation of timolol and betaxolol on lung function in asthmatic subjects." Am Rev Respir Dis 133 (1986): 264-8

19. Frishman WH "Atenolol and timolol, two new systemic beta-adrenoceptor antagonists." N Engl J Med 306 (1982): 1456-62

20. Laursen SO, Bjerrum P "Timolol eyedrop-induced severe bronchospasm." Acta Med Scand 211 (1982): 505-6

21. Botet C, Grau J, Benito P, Coll J, Vivancos J "Timolol ophthalmic solution and respiratory arrest." Ann Intern Med 105 (1986): 306-7

22. Charan NB, Lakshminarayan S "Pulmonary effects of topical timolol." Arch Intern Med 140 (1980): 843-4

23. Sharir M, Nardin GF, Zimmerman TJ "Timolol maleate associated with phalangeal swelling." Arch Ophthalmol 109 (1991): 1650

24. Morris R, Bulteau P "Respiratory arrest after beta-blocker in an asthmatic patient." Med J Aust 2 (1980): 576

25. Perell H, Campbell DG, Vela A, Henderson B "Choroidal detachment induced by a systemic beta-blocker." Ophthalmology 95 (1988): 410-1

26. Coppeto JR "Timolol-associated myasthenia gravis." Am J Ophthalmol 98 (1984): 244-5

27. Coppeto JR "Transient ischemic attacks and amaurosis fugax from timolol." Ann Ophthalmol 17 (1985): 64-5

28. Verkijk A "Worsening of myasthenia gravis with timolol maleate eyedrops." Ann Neurol 17 (1985): 211-2

29. Shore JH, Fraunfelder FT, Meyer SM "Psychiatric side effects from topical ocular timolol, a beta-adrenergic blocker." J Clin Psychopharmacol 7 (1987): 264-7

30. Berstein LP, Henkind P "Additional information on adverse reactions to timolol." Am J Ophthalmol 92 (1981): 295-6

31. Velde TM, Kaiser FE "Ophthalmic timolol treatment causing altered hypoglycemic response in a diabetic patient." Arch Intern Med 143 (1983): 1627

32. Safran AB, Simona F, Sansonetti A, Pometta D, James R "Effects of ocular carteolol and timolol on plasma high-density lipoprotein cholesterol level." Am J Ophthalmol 117 (1994): 683

33. Swenson ER "Severe hyperkalemia as a complication of timolol, a topically applied beta-adrenergic antagonist." Arch Intern Med 146 (1986): 1220-1

34. Leren P, Foss PO, Nordvik B, Fossbakk B "The effect of enalapril and timolol on blood lipids." Acta Med Scand 223 (1988): 321-6

35. Nolan BT "Acute suicidal depression associated with use of timolol." JAMA 247 (1982): 1567

36. Lynch MG, Whitson JT, Brown RH, Nguyean H, Drake MM "Topical beta-blocker therapy and central nervous system side effects: a preliminary study comparing betaxolol and timolol." Arch Ophthalmol 106 (1988): 908-11

37. White HD, Antman EM, Glynn MA, et al "Efficacy and safety of timolol for prevention of supraventricular tachyarrhythmias after coronary artery bypass surgery." Circulation 70 (1984): 479-84

38. Feiler-Ofry V, Godel V, Lazar M "Nail pigmentation following timolol maleate therapy." Ophthalmologica 182 (1981): 153-6

39. Baldone JA, Hankin JS, Zimmerman TJ "Allergic conjunctivitis associated with timolol therapy in an adult." Ann Ophthalmol 14 (1982): 364-5

40. Fernandez-Vozmediano JM, Blasi NA, Romero-Cabrera MA, Carracosa-Cerquero A "Allergic contact dermatitis to timolol." Contact Dermatitis 14 (1986): 252

41. Puig L, Goni FJ, Roque AM, Bordas FD, Morgas JM "Psoriasis induced by ophthalmic timolol preparations." Am J Ophthalmol 108 (1989): 455-6

42. Lustgarten JS "Topical timolol-induced arthropathy." Am J Ophthalmol 105 (1988): 687-8

43. Koch P "Allergic contact dermatitis due to timolol and levobunolol in eyedrops, with no cross-sensitivity to other ophthalmic beta-blockers." Contact Dermatitis 33 (1995): 140-1

It is possible that some side effects of timolol may not have been reported. These can be reported to the FDA here. Always consult a healthcare professional for medical advice.

Disclaimer: Every effort has been made to ensure that the information provided is accurate, up-to-date and complete, but no guarantee is made to that effect. In addition, the drug information contained herein may be time sensitive and should not be utilized as a reference resource beyond the date hereof. This material does not endorse drugs, diagnose patients, or recommend therapy. This information is a reference resource designed as supplement to, and not a substitute for, the expertise, skill , knowledge, and judgement of healthcare practitioners in patient care. The absence of a warning for a given drug or combination thereof in no way should be construed to indicate safety, effectiveness, or appropriateness for any given patient. does not assume any responsibility for any aspect of healthcare administered with the aid of materials provided. The information contained herein is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. If you have questions about the substances you are taking, check with your doctor, nurse, or pharmacist.