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.
Allergies: Some people who are allergic to sulfonamide (or "sulfa") medications may experience a similar allergic reaction to dorzolamide. Before you use dorzolamide - timolol eye drops, inform your doctor about any previous adverse reactions you have had to medications, especially sulfonamide antibiotics or diabetes medications. Contact your doctor if you experience a skin rash while using this medication. Stop using this medication and get medical attention if you experience hives; shortness of breath; peeling or blistering skin; or swelling of the mouth, lips, tongue, or throat.
Blurry vision: Side effects such as blurred vision may affect the ability to drive and operate machinery. Avoid driving, operating machinery, or performing other tasks which require you to see clearly until your vision has cleared.
Choroidal detachment: Anyone with chronic or recurrent choroidal detachment should talk to their doctor about further use of the eye drop.
Contact lenses: The preservative used in the eye drops (benzalkonium chloride) may be absorbed by soft contact lenses. Contact lenses should be removed before using the eye drops and not reinserted for at least 15 minutes. The preservative-free eye drops have not been studied for use by people who wear contact lenses.
Eye surgery, eye (corneal) defect, infections, trauma: Anyone using this medication who has had eye surgery, preexisting long-term eye (corneal) defect, trauma to the eye, or who has symptoms of an eye infection (e.g., eye redness, itchiness, discharge, crusts on the eyelids, or the feeling of something in the eye) should contact their doctor concerning further use of the eye drop.
General: As with other topically applied eye drops, this medication may be absorbed into the bloodstream. The same side effects reported with oral medications from the families known as beta-blockers (e.g., timolol, propranolol, metoprolol) or sulfonamides (e.g., sulfamethoxazole) may occur with the eye drops. These side effects may include, but are not limited to, shortness of breath, dizziness, lightheadedness, rash, or slow heartbeat. Refer to the section, "What side effects are possible with this medication?" for more information.
Liver function: This medication has not been studied in people with liver function impairment. If you have liver 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.
Low blood sugar: People who are prone to low blood sugar and people with diabetes should closely monitor their blood sugar while using this medication as it may mask the signs of low blood sugar.
Medical conditions: Timolol belongs to the family of medications known as beta-blockers. Although timolol is given as an eye drop, small amounts may be absorbed into the bloodstream. For this reason, it should not be used by anyone who must avoid internal use of beta-blockers. This includes those with abnormally low heart rate, certain abnormal heart rhythms, uncontrolled congestive heart failure, asthma, or severe chronic obstructive pulmonary disease.
Muscle weakness: Beta-blockers such as timolol have been reported to increase muscle weakness associated with certain symptoms, such as double vision or generalized weakness. If you experience these symptoms, contact your doctor.
Overactive thyroid: Timolol may mask the signs of overactive thyroid. If you have an overactive thyroid gland (hyperthyroidism), 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. People who have this condition or are prone to developing it should be carefully monitored by their doctors.
Pregnancy: This medication should not be used during pregnancy unless the benefits outweigh the risks. If you become pregnant while using this medication, contact your doctor immediately.
Breast-feeding: It is not known if dorzolamide passes into breast milk. Timolol does pass into breast milk. If you are a breast-feeding mother and are using this medication, it may affect your baby. Talk to your doctor about whether you should continue breast-feeding.
The safety and effectiveness of this medication have not been established for children.