Pemirolast (Ophthalmic)

As a mast cell stabilizer, Pemirolast is an effective anti-allergy drug therapy.


Pemirolast is a mast cell stabilizer. It functions by preventing the release of certain chemicals within the eye that can cause symptoms of allergy. It is an off-yellow powder which is water soluble, and as such can be used as part of a sterile aqueous solution, administered as an eye drop, to prevent itching and discomfort associated with conditions like hay fever and conjunctivitis.

Certain inflammatory mediators such as leukotriene and histamine cause allergies when they have been released from the mast cells or basophils. These mediators react with tissues via the histamine receptors, producing vasodilation and pruritic. As an agonist to histamine and leukotrienes, Pemirolast competes with these chemicals on the effector cells of the blood vessels, providing temporary relief of itching and watery eyes.

Type Of Medicine

  • Mast cell stabilizer

Conditions Treated

Side Effects

Pemirolast can cause some unwanted side effects along with its desired effects. The most common side effects reported by patients undergoing treatment with this medication include the following:

  • Headache
  • Stuffy or runny nose
  • Burning sensation in the eye
  • General discomfort in the eye
  • Itching of the eye
  • A feeling of something being present in the eye
  • Dry eyes
  • Hives
  • Rash
  • Difficulty breathing
  • Fever

As the patient continues to take Pemirolast as prescribed by a doctor, the majority (if not all) of the previously mentioned side effects should begin to lessen. If side effects persist over time or appear to get worse, the patient is advised to consult their doctor or healthcare provider immediately. In some instances, a doctor or pharmacist may be able to recommend over the counter remedies or other prescription drugs to treat side effects which are causing discomfort.

Typically, most patients will only experience minimal side effects while using Pemirolast, if they notice any whatsoever. The drug is designed to alleviate many of the previously mentioned side effects, and should get to work after the patient has been taking it for a number of days. Most doctors agree that the benefits of treating allergies outweigh the risk of experiencing temporary side effects.

Because Pemirolast can affect vision, patients are advised to refrain from driving or operating heavy machinery until their symptoms dissipate. This is in order to protect both the patient and other road users from the risk of injury.

Not all side effects may be listed. In the event of experiencing side effects which are undocumented, the patient is advised to contact their doctor as soon as is practical and to notify the FDA of any potential findings.


As with all drugs, it is very important for the patient to only take Pemirolast as prescribed by a doctor. This means that patients should avoid taking any more of the drug than they have been advised to, either in terms of dose size or frequency. In addition to this, patients should refrain from taking Pemirolast if told to by a doctor, even if they still have a supply of the medicine remaining.

Pemirolast is designed for use in the eye only, and patients are advised to avoid contact of any other mucous membranes with this drug. As a general rule, it should be administered once every four hours, when the patient is awake.

To use Pemirolast, the patient should first wash their hands to avoid the risk of any unnecessary contamination or infection. The patient should then pull the lower eyelid away from the eye with their index finger, forming a pouch. One Pemirolast eye drop should then be administered into the lower eyelid before the patient gently closes their eye. The index finger should then be used to apply pressure to the inner corner of the eye for at least one to two minutes. During this time, the patient should not blink. Any excess medication can be removed from around the eye with a clean tissue, although the patient should be careful to avoid touching the actual eye itself.

After the medicine has been administered, the patient should wash their hands to remove any excess Pemirolast which may have inadvertently landed on them. To prevent bacteria from contaminating the medicine, the applicator tip of the container should not touch any surfaces, including the eye. The container should be kept tightly closed when not in use.

Most patients notice a decrease in the level of eye itching within a few days of Pemirolast use. However, it can take up to four weeks before the patient notices any real benefit.

While the manufacturers of Pemirolast provide general dose instructions, it should be reiterated that these are merely guidelines which can be altered by the patient's doctor. A doctor will consider the age, height, weight, and condition of the patient, among other factors, when determining dosage. There are no recommended dose sizes for children. Instead, the manufacturer of Pemirolast leaves pediatric dose size and frequency to the administering doctor.

Patients are advised against taking double doses. If a patient misses a dose, they should take the missed dose as soon as they realize' unless it is nearer the time for the next scheduled dose, in which case the patient should omit the missed dose and take the next scheduled dose before continuing with their administration regimen as normal.

Patients who experience symptoms of overdose (pressure or severe pain in the eye, difficulty breathing, and/or flushed skin) may require immediate medical attention and are advised to contact their local poison control center on 1800-222-1222 or emergency services on 911.


All drugs have the potential to interact with other chemicals or drugs present in the human body, and these interactions can change the effects of one or more of the involved medications. In some cases, this can cause a medication to become ineffective in treating a condition. In other cases, interactions can create dangerous or even fatal side effects. Because of these risks, it is incredibly important for patients to keep a full and detailed list of all medicines they are currently undergoing treatment with, including dose sizes and frequency of administration. This extends to complementary medicines, over the counter remedies, herbal supplements, and vitamins, as well as prescribed drugs.

While there are no documented negative interactions between Pemirolast and other medicines, this does not mean that interactions do not exist. It is possible that Pemirolast could interact with other eye drops or ocular medications, and healthcare professionals advise that Pemirolast should not be administered at the same time as other ocular treatments.


Patients who are allergic to any of the ingredients listed in Pemirolast are advised to inform their doctor. Patients who have previously experienced allergic reactions to other medications should also inform their doctor. This is because Pemirolast could contain active or inactive ingredients known to cause allergic reactions.

Before using Pemirolast, patients should be aware that certain conditions could affect the way the medication works. Patients who fall into the following categories should discuss the risks of taking the drug:

  • If they are pregnant, intending on becoming pregnant soon or are breastfeeding.
  • If they have any allergies to foods or other substances.

Pemirolast should be used with extreme caution in children younger than three years of age. This is because effectiveness and safety has not yet been established within this age group.

Patients who experience red or pink eye should avoid wearing soft contact lenses. Even if the patient does not experience pink eye, they should wait for at least ten minutes before inserting their contact lenses after administering Pemirolast.


Pemirolast should be stored at room temperature (between 15C and 25C) in the packaging it was shipped in, away from sources of moisture, heat, and light. It is therefore unsuitable for storage in a bathroom cabinet, and should instead be kept out of reach of children and pets in a dedicated, locked medicine cabinet where possible. To get rid of unwanted, unused or expired Pemirolast, patients should consult FDA guidelines on medication disposal.


While Pemirolast is an effective means of keeping eye allergies under control, it can also pose a risk to patients who do not communicate fully with their healthcare providers. As a treatment designed to alleviate symptoms of conjunctivitis and hay fever, it stops itching and excess water in the eyes. However, it can also cause a burning sensation, headaches, and runny nose, potentially impairing the day-to-day functionality of the patient if the proper precautions are not taken. For this reason, it is important for the patient to be honest about their medical history, as this allows their doctor to impart the best possible advice and to decide upon the most suitable course of treatment.

When taken correctly, Pemirolast can provide relief from the symptoms of eye allergies which may have otherwise been untreatable. This provides the patient with a much greater quality of life' but in order to achieve this, patient and doctor must work together to ascertain the appropriate Pemirolast dosage and frequency of use.