Generic name: phenylephrine [ fen-il-EF-rin ]
Drug classes: Mydriatics, Ophthalmic antihistamines and decongestants
Medically reviewed by Drugs.com. Last updated on Nov 2, 2022.
Uses for Mydfrin
Ophthalmic phenylephrine in strengths of 2.5 and 10% is used to dilate (enlarge) the pupil. It is used before eye examinations, before and after eye surgery, and to treat certain eye conditions. In the U.S., these preparations are available only with your doctor's prescription.
Before using Mydfrin
In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For this medicine, the following should be considered:
Tell your doctor if you have ever had any unusual or allergic reaction to this medicine or any other medicines. Also tell your health care professional if you have any other types of allergies, such as to foods, dyes, preservatives, or animals. For non-prescription products, read the label or package ingredients carefully.
Children may be especially sensitive to the effects of phenylephrine. This may increase the chance of side effects during treatment. In addition, the 10% strength is not recommended for use in infants. Also, the 2.5 and 10% strengths are not recommended for use in low birth weight infants.
Repeated use of 2.5 or 10% phenylephrine may increase the chance of problems during treatment with this medicine. In addition, heart and blood vessel problems have occurred more often in elderly patients than in younger adults.
There are no adequate studies in women for determining infant risk when using this medication during breastfeeding. Weigh the potential benefits against the potential risks before taking this medication while breastfeeding.
Interactions with Medicines
Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are taking this medicine, it is especially important that your healthcare professional know if you are taking any of the medicines listed below. The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive.
Using this medicine with any of the following medicines is not recommended. Your doctor may decide not to treat you with this medication or change some of the other medicines you take.
Using this medicine with any of the following medicines is usually not recommended, but may be required in some cases. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.
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Using this medicine with any of the following medicines may cause an increased risk of certain side effects, but using both drugs may be the best treatment for you. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.
Interactions with Food/Tobacco/Alcohol
Certain medicines should not be used at or around the time of eating food or eating certain types of food since interactions may occur. Using alcohol or tobacco with certain medicines may also cause interactions to occur. The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive.
Other Medical Problems
The presence of other medical problems may affect the use of this medicine. Make sure you tell your doctor if you have any other medical problems, especially:
- Type 2 diabetes mellitus or
- Heart or blood vessel disease or
- High blood pressure—The 2.5 and 10% strengths of phenylephrine may make the condition worse
- Idiopathic orthostatic hypotension (a certain kind of low blood pressure)—Use of this medicine may cause a large increase in blood pressure to occur
Proper use of Mydfrin
Do not use if the solution turns brown or becomes cloudy.
- First, wash your hands. Tilt the head back and, pressing your finger gently on the skin just beneath the lower eyelid, pull the lower eyelid away from the eye to make a space. Drop the medicine into this space. Let go of the eyelid and gently close the eyes. Do not blink. Keep the eyes closed and apply pressure to the inner corner of the eye with your finger for 2 or 3 minutes to allow the medicine to be absorbed by the eye.
- Immediately after using the eye drops, wash your hands to remove any medicine that may be on them.
- To keep the medicine as germ-free as possible, do not touch the applicator tip to any surface (including the eye). Also, keep the container tightly closed.
For patients using the 2.5 or 10% eye drops:
- It is very important that you use this medicine only as directed. Do not use more of it and do not use it more often than your doctor ordered. To do so may increase the chance of too much medicine being absorbed into the body and the chance of side effects. This is especially important when this medicine is used in children or in patients with heart disease or high blood pressure, since high doses of this medicine may cause an irregular heartbeat and an increase in blood pressure.
The dose of this medicine will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of this medicine. If your dose is different, do not change it unless your doctor tells you to do so.
The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.
- For ophthalmic solution (eye drops) dosage form:
- For eye redness:
- Adults and children—Use one drop of 0.12% solution every three or four hours as needed.
- For eye exams:
- Adults and children—Use one drop of 2.5% solution. Depending on the eye test to be done, it will take from fifteen minutes to one or two hours for the medicine to work before you can have the eye test.
- For use before eye surgery:
- Adults and teenagers—Use one drop of 2.5 or 10% solution thirty to sixty minutes before the start of eye surgery.
- Children—Use one drop of 2.5% solution thirty to sixty minutes before the start of eye surgery.
- For certain eye conditions:
- Adults and teenagers—Depending on the eye condition being treated, your doctor may tell you to use one drop of 2.5 or 10% solution in the eye from once a day to three times a day.
- Children—Depending on the eye condition being treated, your doctor may tell you to use one drop of 2.5% solution in the eye from once a day to three times a day.
- For eye redness:
If you miss a dose of this medicine, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and go back to your regular dosing schedule. Do not double doses.
For non-prescription strength eye drops, follow the package directions.
Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light. Keep from freezing.
Keep out of the reach of children.
Do not keep outdated medicine or medicine no longer needed.
Precautions while using Mydfrin
If eye pain or change in vision occurs or if redness or irritation of the eye continues, gets worse, or lasts for more than 72 hours, stop using the medicine and check with your doctor.
For patients using the 2.5 or 10% eye drops:
- After you apply this medicine to your eyes, your pupils will become unusually large. This will cause your eyes to become more sensitive to light than they are normally. When you go out during the daylight hours, even on cloudy days, wear sunglasses that block ultraviolet (UV) light to protect your eyes from sunlight and other bright lights. Ordinary sunglasses may not protect your eyes. If you have any questions about the kind of sunglasses to wear, check with your doctor. Also, if this effect continues for longer than 12 hours after you have stopped using this medicine, check with your doctor.
Side Effects of Mydfrin
Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.
Check with your doctor as soon as possible if any of the following side effects occur:
Symptoms of too much medicine being absorbed into the body- Less common with 10% solution; rare with 2.5% or weaker solution
- fast, irregular, or pounding heartbeat
- increased sweating
- increase in blood pressure
Some side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:
More common with 2.5 or 10% solution
- Burning or stinging of eyes
- headache or browache
- sensitivity of eyes to light
- watering of eyes
- Eye irritation not present before use of this medicine
Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.
Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.
More about Mydfrin (phenylephrine ophthalmic)
- Check interactions
- Compare alternatives
- Side effects
- Dosage information
- During pregnancy
- Drug class: mydriatics
- En español
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