Phenylephrine (Ophthalmic)

Available in a variety of strengths, Phenylephrine can be used to enlarge the pupil of the eye prior to examinations or surgery.


Phenylephrine, which is often marketed under the brand names Altafrin, Mydfrin, Neofrin, Eye Cool and Ocu-Phrin, is a decongestant which shrinks blood vessels to provide relief. When applied to the eyes, it can relieve dryness, irritation, burning and redness caused by extreme weather conditions or irritation.

It can also be used to constrict vessels in the eye and dilate the pupils to make eye surgery or examinations easier. It is often used in conjunction with a tropicamide, and should be administered after a topical anesthetic has been applied. The constrictions caused by Phenylephrine use can also alleviate symptoms of com/health/coma/">glaucoma although it is not suitable for the treatment of narrow angle glaucoma, and can contribute to making this condition worse. Regular, extended use of this medication can cause narrow angle glaucoma.

Phenylephrine can also be prescribed off-label, at the discretion of a prescribing doctor, to treat conditions it is not typically associated with or approved by the FDA for.

Type Of Medicine

  • Adrenic receptor agonist

Conditions Treated

  • Glaucoma
  • Dryness of the eye
  • Irritation of the eye

Side Effects

Like all medicines, Phenylephrine can cause unwanted side effects along with its desired effects. The most commonly reported side effects by patients undergoing treatment with this medicine include the following:

  • Paleness
  • Trembling
  • Increased blood pressure
  • Fast, irregular pounding heartbeat
  • Increased sweating
  • Dizziness
  • Watering of the eyes
  • Sensitivity to light
  • Brow or headache
  • Stinging or burning in the eyes
  • Irritation of the eyes

As the patient continues to undergo treatment with Phenylephrine as prescribed by a doctor, many of these side effects should lessen. If any side effects persist for a prolonged period or appear to get worse, the patient should contact their doctor as soon as possible. In many instances, a doctor or pharmacist should be able to recommend over the counter remedies or prescription medication to alleviate the discomfort caused by side effects.

Generally, the majority of patients will only experience minimal side effects, and many won't experience side effects at all while using Phenylephrine. Most doctors and healthcare professionals agree that the benefit of using Phenylephrine outweighs the risk of experiencing mild side effects.

Other side effects, which are experienced rarely, albeit often enough to warrant mentioning, include the following:

  • Anxiety
  • Unusual tiredness or weakness
  • Dangerously high blood pressure
  • Easy bleeding or bruising
  • Swelling of the lips, face, throat or tongue

Because Phenylephrine eye drops can affect vision, patients are advised to refrain from driving or operating heavy machinery immediately after this drug has been administrated. This is to avoid putting the patient or other road users at risk.

This medication can also cause anxiety. Caution should therefore be exercised when it is prescribed to patients with a history of mental health problems (such as depression, schizophrenia or bipolar disorder).

Not all side effects may be listed or reported. Patients who believe they may have experienced unreported side effects are advised to contact their doctor as soon as possible, and to report their findings to the FDA if they wish.


Like all medicines, it is important to only take Phenylephrine as prescribed by a qualified physician. This means that patients should avoid taking any more of the drug than advised, both in terms of dose size and frequency. In addition to this, patients should be prepared to cease taking Phenylephrine if asked to do so by their doctor, even if they still have a supply of the medicine remaining.

Phenylephrine is available in concentrations of 2.5 per cent and 10 per cent. Most conditions can be sufficiently treated with the 2.5 per cent solution, although some patients may require the 10 per cent version to obtain a larger decree of mydriasis. Adults should apply no more than three drops of Phenylephrine solution per day.

To correctly administer Phenylephrine eye drops, patients should do the following:

  • Wash their hands prior to handling or using Phenylephrine drops. This prevents contamination.
  • Tilt their head back.
  • Pull the lower lid of the eye downwards.
  • Hold the bottle of Phenylephrine drops upside down, and bring it close to the eye. Patients should avoid touching the eye with their hands or the bottle.
  • Apply pressure to the bottle, enough to release one drop of the Phenylephrine solution into the eye. If patients require more than one drop, they should wait a minimum of three to five minutes before applying the second or third drops, and not exceed more than three drops in total.
  • The eye should be closed after drops have been administered for at least two minutes. Patients are advised to press gently on the side of the nose, in the corner where the eye meets the nose. This helps to keep the drops from draining into the throat or nose, keeping the Phenylephrine solution within the eye area.
  • This process should be repeated in the other eye only if the prescribing doctor has advised treatment of both eyes.
  • Replace the cap on the bottle of Phenylephrine and store it in a safe place.

When administering Phenylephrine, patients should exercise caution and advoid touching the tip of the eye dropper on any surfaces. If any excess Phenylephrine solution drips onto the skin, the patient should clean it off with tepid or warm water.

To lessen the possibility of systemic absorption, the patient should apply pressure to the relevant tear duct after administering Phenylephrine.

While the manufacturer of this medicine provides general dosage instructions, it must be reiterated that these are simply guidelines, which can be altered at the discretion of the prescribing doctor. A doctor will take the age, height, weight, size and condition of the patient into account, among other factors, when deciding on the optimal dose size.

The manufacturer does not suggest a recommended dose for children, even though this medicine can be used on children. The prescribing physician should choose the optimum pediatric dose.

Patients are warned against administering double doses. If a patient misses a dose, they are advised to administer the dose as soon as they realize. If this is not possible, or it is closer to the time of the next due dose, the patient should simply omit the missed dose, take the next scheduled dose and continue with the schedule from thereon in as normal.

If the patient experiences signs of an overdose (fast heartbeat, headache, ocular pressure, nausea, vomiting and/or loss of co-ordination) they should seek medical attention imminently, by contacting their local poison control center on 1800-222-1222 or emergency services on 911. The patient should make their way to the nearest ER room immediately, providing it is in close enough proximity.


All medicines have the potential to interact with other medications or chemicals within the body. Some medicines can even interact with foods and drinks. Interactions can cause changes to the way one or more medications work. In some cases, this can result in a medicine becoming ineffective in treating the condition it was prescribed for. In other cases, interactions can cause dangerous and even fatal side effects.

Because of these risks, patients are advised to keep a full, detailed list of all medications they are currently taking. This extends to complimentary medicines, over the counter remedies, vitamins and herbal supplements, as well as prescribed drugs.

The following is a list of medications known to interact negatively with Phenylephrine. Patients who are currently undergoing treatment with any of these medicines should inform their doctor or healthcare provider prior to beginning a course of Phenylephrine eye drops:

  • Trihexyphenidyl
  • Tranylcypromine
  • Timolol Ophthalmic
  • Timolol
  • Terbutaline
  • Tapentadol
  • Sotalol
  • Sibutramine
  • Selegiline
  • Scopolamine
  • Salmeterol
  • Safinamide
  • Ritodrine
  • Reserpine/Trichlormethiazide
  • Reserpine
  • Rauwolfia Serpentina
  • Rasagiline
  • Racepinephrine
  • Propranolol
  • Propantheline
  • Procyclidine
  • Procarbazine
  • Polythiazide/Reserpine
  • Pirbuterol
  • Pindolol
  • Phenelzine
  • Penbutolol
  • Oxybutynin
  • Orphenadrine
  • Olodaterol/Tiotropium
  • Olodaterol
  • Nebivolol/Valsartan
  • Nebivolol
  • Nadolol
  • Milnacipran
  • Midodrine
  • Metoprolol
  • Metipranolol Ophthalmic
  • Methysergide Maleate
  • Methylergonovine
  • Methylene Blue
  • Methyclothiazide/Reserpine
  • Methscopolamine/Pseudoephedrine
  • Methscopolamine/Phenylephrine
  • Methscopolamine
  • Metaproterenol
  • Mepenzolate
  • Linezolid
  • Levomilnacipran
  • Levobunolol Ophthalmic
  • Levobetaxolol Ophthalmic
  • Levalbuterol
  • Lactobacillus Acidophilus/Methscopolamine
  • Labetalol
  • Isoproterenol/Phenylephrine
  • Isoproterenol
  • Isoetharine
  • Isocarboxazid
  • Indacaterol
  • Hyoscyamine/Phenyltoloxamine
  • Hyoscyamine/Phenobarbital
  • Hyoscyamine/Methenamine/Methylene Blue/Sodium Biphosphate
  • Hyoscyamine/Methenamine/Methylene Blue/Phenyl Salicylate/Sodium Biphosphate
  • Hyoscyamine/Methenamine/Methylene Blue/Phenyl Salicylate
  • Hyoscyamine/Methenamine
  • Hyoscyamine
  • Hydroflumethiazide/Reserpine
  • Hydrochlorothiazide/Timolol
  • Hydrochlorothiazide/Reserpine
  • Hydrochlorothiazide/Propranolol
  • Hydrochlorothiazide/Metoprolol
  • Hydralazine/Hydrochlorothiazide/Reserpine
  • Homatropine/Hydrocodone
  • Halothane
  • Guanethidine/Hydrochlorothiazide
  • Guanethidine
  • Guanadrel
  • Glycopyrrolate/Indacaterol
  • Glycopyrrolate
  • Furazolidone
  • Formoterol/Mometasone
  • Formoterol/Glycopyrrolate
  • Formoterol
  • Fluticasone/Vilanterol
  • Fluticasone/Umeclidinium/Vilanterol
  • Fluticasone/Salmeterol
  • Flavoxate
  • Esmolol
  • Ergotamine
  • Ergonovine
  • Duloxetine
  • Droxidopa
  • Dorzolamide/Timolol Ophthalmic
  • Dihydroergotamine
  • Dicyclomine
  • Dexchlorpheniramine/Methscopolamine/Pseudoephedrine
  • Dexchlorpheniramine/Methscopolamine/Phenylephrine
  • Desvenlafaxine
  • Deserpidine/Methyclothiazide
  • Deserpidine/Hydrochlorothiazide
  • Deserpidine
  • Clidinium
  • Chlorthalidone/Reserpine
  • Chlorpheniramine/Methscopolamine/Pseudoephedrine
  • Chlorpheniramine/Methscopolamine/Phenylpropanolamine
  • Chlorpheniramine/Methscopolamine/Phenylephrine/Pseudoephedrine
  • Chlorpheniramine/Methscopolamine/Phenylephrine
  • Chlorpheniramine/Methscopolamine
  • Chlorpheniramine/Guaifenesin/Methscopolamine/Phenylephrine
  • Chlorpheniramine/Dextromethorphan/Methscopolamine
  • Chlorpheniramine/Dextromethorphan/Guaifenesin/Methscopolamine/Phenylephrine
  • Chlorothiazide/Reserpine
  • Chlordiazepoxide/Methscopolamine
  • Chlordiazepoxide/Clidinium
  • Cellulase/Hyoscyamine/Pancrelipase/Phenyltoloxamine
  • Carvedilol
  • Carteolol Ophthalmic
  • Carteolol
  • Carbinoxamine/Methscopolamine/Pseudoephedrine
  • Caffeine/Ergotamine
  • Butabarbital/Hyoscyamine/Phenazopyridine
  • Budesonide/Formoterol
  • Brompheniramine/Chlorpheniramine/Methscopolamine/Phenylephrine/Pseudoephedrine
  • Brimonidine/Timolol Ophthalmic
  • Bitolterol
  • Bisoprolol/Hydrochlorothiazide
  • Bisoprolol
  • Biperiden
  • Betaxolol Ophthalmic
  • Betaxolol
  • Benztropine
  • Benzoic Acid/Hyoscyamine/Methenamine/Methylene Blue/Phenyl Salicylate
  • Bendroflumethiazide/Rauwolfia Serpentina
  • Bendroflumethiazide/Nadolol
  • Belladonna/Opium
  • Belladonna/Ergotamine/Phenobarbital
  • Belladonna/Butabarbital
  • Belladonna
  • Atropine/Pralidoxime
  • Atropine/Phenobarbital
  • Atropine/Hyoscyamine/Phenobarbital/Scopolamine
  • Atropine/Edrophonium
  • Atropine/Diphenoxylate
  • Atropine/Difenoxin
  • Atropine/Chlorpheniramine/Hyoscyamine/Pseudoephedrine/Scopolamine
  • Atropine/Chlorpheniramine/Hyoscyamine/Phenylephrine/Scopolamine
  • Atropine/Chlorpheniramine/Hyoscyamine/Phenylephrine/Phenylpropanolamine/Scopolamine
  • Atropine
  • Atenolol/Chlorthalidone
  • Atenolol
  • Aspirin/Caffeine/Orphenadrine
  • Arformoterol
  • Anhydrous Calcium Iodide/Isoproterenol
  • Amylase/Cellulase/Hyoscyamine/Lipase/Phenyltoloxamine/Protease
  • Albuterol/Ipratropium
  • Albuterol
  • Acebutolol


Patients who are allergic to this medicine or any other medication should inform their doctor prior to taking it. This is because Phenylephrine ophthalmic solution could contain active or inactive ingredients which could potentially cause allergies.

Doctors advise that patients should refrain from using Phenylephrine if they are currently suffering from an eye infection or an eye injury, or if they have recently had eye surgery performed.

When prescribing this medicine, a doctor may ask the patient if they have any medical conditions which could potentially be exacerbated by the use of Phenylephrine eye drops, including the following:

  • High blood pressure
  • Coronary heart disease
  • Hardened arteries
  • Any type of heart condition
  • Asthma
  • Sulfite allergy

Phenylephrine is classified as an FDA pregnancy category C medication. This means that it is unknown whether it could possibly harm an unborn baby. Women who are pregnant or intending on becoming pregnant should discuss this with their doctor while using this medicine or before using this medicine.

It is unknown whether Phenylephrine is excreted into breast milk, or whether it could potentially harm a nursing baby. However, as a general rule, breastfeeding women are advised to only take medicines if they really need to, and if the benefits outweigh the risks.

Phenylephrine should not be given to children without the caregiver or responsible adult seeking expert medical advice beforehand. This is because standard adult doses may have greater effect on younger children.

This medicine should not be used for more than three days in a row. If symptoms have not improved after three days, the patient should arrange an appointment to discuss the condition with their doctor, who may prescribe an alternative treatment or book the patient in for more extensive examinations.

Long-term use of this medicine could potentially damage the blood vessels in the eyes. If untreated, this can eventually lead to blindness.


Phenylephrine eye drops should be stored at room temperature, away from sources of light, moisture and heat. This medicine is therefore unsuitable for storing in a bathroom cabinet, and should instead be kept in a dedicated, locked medicine cupboard where possible, out of the reach of pets and children.

Patients who need to dispose of unwanted, unused or expired Phenylephrine should do so in a safe and hygenic manner, in accordance with state law and FDA guidelines. Patients should not discard of unwanted Phenylephrine by flushing it down the toilet or drain. Many pharmacies offer medication take back schemes, where they will recycle or safely dispose of unused medications. Patients are advised to take advantage of these schemes.


While Phenylephrine is an incredibly beneficial drug for those suffering from eye irritations, or those who require pupil dilation, it can also pose something of a risk to patients who do not communicate properly with their healthcare providers. It relieves dryness, itchiness and irritation, but can also cause unwanted side effects such as increased ocular pressure or vein and artery problems within the eye. It can also cause blurred vision, which can put the patient at risk of entering perilous situations if the correct precautions are not taken.

Because of these risks, it is important for the patient to be upfront and forthcoming about their own medical history, and to inform their doctor or healthcare provider of any hereditary illnesses which run in the family.

When used correctly, Phenylephrine is useful for treating eye irritations and for dilating the pupil prior to surgery or ocular examinations. However, to achieve this, the patient and doctor must work together in order to ascertain the best dosage and frequency.