Natamycin (Ophthalmic)


When patients are exhibiting signs of an eye infection, it's necessary to determine whether the infection has been caused by bacteria, fungi or a virus. Once this has been established, the exact type of fungus, bacteria or virus causing the infection must also be identified. If the patient has a fungal eye infection, an anti-fungal treatment must be used to control their symptoms and rid the body of infection.

Natamycin can be used to treat fungal infections which are affecting the eye, cornea and/or conjunctiva. Once the medication takes effect, it prevents glucose and amino acids from being moved across the plasma membrane. By binding to ergosterol, Natamycin prevents membrane transport proteins from taking effect. As the amino acids and glucose are now longer being transported across the plasma membrane, the growth of the fungi is inhibited. As a result, the patient's condition does not worsen and the existing infection is destroyed.

Although Natamycin can be administered in various forms, it is typically prescribed in the form of eye drops when patients have an infection which is affecting this part of the body. Whilst Natamycin eye drops are extremely effective in treating fungal eye infections, they will not treat bacterial eye infections or eye infections which are viral in nature.

When patients use Natamycin eye drops, they may notice an improvement in their symptoms fairly quickly. However, patients should continue to use the medication and should finish the course of treatment that's been prescribed. This ensures that the infection has been resolved and that it is not likely to recur once the medication has been discontinued.

Conditions Treated

  • Fungal eye infections

Type Of Medicine

  • Antifungal agent

Side Effects

Although patients can experience adverse effects when using any type of medication, there are relatively few side effects associated with Natamycin. However, if patients exhibit any of the following symptoms when using Natamycin eye drops, they should obtain immediate medical help:

  • Eye pain
  • Change in eyesight
  • Very bad eye irritation
  • Itching
  • Hives
  • Rash on the skin
  • Blistered, peeling or swollen skin
  • Fever
  • Tightness in the chest or throat
  • Difficulty talking
  • Difficulty breathing
  • Wheezing
  • Unusual hoarseness
  • Swelling of the face, mouth, tongue, lips or throat

The above side effects may indicate that the patient is having an allergic reaction to the medication and it's vital that they obtain emergency medical treatment. If patients experience any other side effects when using Natamycin eye drops, they should also seek medical advice.


When patients are prescribed Natamycin, their physician will tell them how much medication to use and how often it should be applied. Generally, adult patients are advised to use one drop in the affected eye(s) every four to six hours. However, if a serious infection is present, patients may be advised to administer one drop in the affected eye(s) every one to two hours for the first three or four days of treatment. Following this, patients may reduce their dose to one drop in the affected eye(s) six to eight times per day.

Before applying Natamycin eye drops, patients should wash their hands thoroughly to avoid introducing germs into the affected area. Following this, patients should press lightly on their lower eyelids. This will draw the eyelid away from the eye and create a space into which the medication can be administered.

Patients should then drop the appropriate dose of Natamycin into the eye and close their eyes for one to two minutes. During this time, patients should try not to blink and should keep their eyes shut. This helps the medication to reach the appropriate areas of the eye and ensures that it is properly absorbed.

When using Natamycin eye drops, patients should ensure that the applicator does not come into contact with any substances, including the eye itself. This helps to prevent germs from being introduced to the eye and also prevents the spread of infection.

In order to be effective, Natamycin eye drops should be used regularly and administered in accordance with the patient's treatment schedule. However, if patients forget to administer a dose of medication, they should do so as soon as they remember to. If their next dose is almost due, patients should skip the missed dose and continue with the usual dosing routine. Patients should not attempt to administer a double or extra dose of Natamycin, even if a previous dose has been missed.

If patients are unsure how to use Natamycin eye drops or when to administer the medication, they should seek advice from their physician or pharmacist.

Potential Drug Interactions:

Although some medications can be used together, others may cause a drug interaction to occur if they are used at the same time. Due to this, patients should tell their physician if they are taking any other medicines, supplements or vitamins before they start using Natamycin eye drops.

Similarly, patients should obtain medical advice before they start using any new medicines, supplements or vitamins once they have started treatment with Natamycin.


If patients have any other existing health conditions, they should inform their physician before Natamycin eye drops are prescribed. There are some conditions which may affect the patient's use of Natamycin. By disclosing their medical history and current health problems, patients can ensure that Natamycin is safe for them to use and that they are being prescribed the most suitable medication for their infection.

As the effects of Natamycin on pediatric patients are unknown, this medication is not normally prescribed to children or infants.

When patients are using Natamycin eye drops, their physician will check their progress regularly. This is to ensure that the medication is having the desired effect and that the infection is being adequately treated. In some cases, patients may need to have check-ups numerous times per week when they are using Natamycin eye drops.

Generally, patients will notice an improvement in their symptoms fairly quickly when they are using Natamycin. However, if the patient's symptoms worsen or do not improve within seven to ten days of using this medication, they should contact their physician for further advice.

Natamycin has been classed as a category C drug in terms of pregnancy and should not be used by patients who are currently pregnant. As a category C medication, Natamycin could cause harm to the unborn fetus if it is used by a patient who is pregnant.

If patients become pregnant when using Natamycin, they should notify their physician straight away.

Although some medications can be excreted in breast milk, it is not known if Natamycin can be transferred to an infant in this way. Similarly, it is not known whether Natamycin would pose a risk to the infant if it was transferred via breast milk. Due to this, patients are usually advised not to breastfeed whilst using Natamycin as it could pose a risk to the infant.

Before using Natamycin eye drops, patients should tell their doctor if they have any known allergies or if they have ever exhibited an allergic reaction to any substances. This includes any allergies to medicines, foods, preservatives, animals and/or dyes. In rare cases, Natamycin can cause patients to develop a serious allergic reaction. The symptoms of an allergic reaction may include:

  • Itching
  • Difficulty swallowing
  • Hives
  • Fever
  • Rash on the skin
  • Gasping for breath
  • Swollen, blistering or peeling skin
  • Hoarseness
  • Tightness in the chest or throat
  • Difficulty talking
  • Shortness of breath
  • Difficulty breathing
  • Wheezing
  • Swelling of the lips, throat, face, tongue, mouth or hands

As an allergic reaction can be life-threatening, patients should seek emergency medical treatment if they experience the above symptoms.


As patients are usually advised to use Natamycin eye drops more than once per day, they will need to keep their medication at home. However, it's important that Natamycin is stored in a safe location and that children and/or pets cannot gain access to it.

When storing Natamycin at home, patients should adhere to the manufacturer's instructions. In most cases, Natamycin eye drops can be kept at room temperature but should be kept in a closed container at all times. In addition to this, Natamycin should be protected from moisture, heat and direct light.

If the medication reaches its use-by date or if patients are advised to stop using Natamycin, they should dispose of the medication carefully. Patients should contact their physician's office or pharmacist and make use of a specialist medicine disposal service.


If patients develop a fungal eye infection, they can experience a range of symptoms. Eye pain, irritation, redness, swelling and itching are not uncommon when an eye infection occurs and patients may struggle to perform daily tasks if treatment is not instigated.

Once patients start using Natamycin eye drops, they should obtain swift relief from their symptoms. Although they may need to use Natamycin for some time in order to ensure the infection has been fully resolved, the symptoms associated with their infection should be relieved in a relatively short amount of time.