Fluconazole – Side Effects, Dosage, and Uses

Fluconazole

Fluconazole is an anti-fungal that can come in the form of a suspension, a tablet which can both be taken by mouth. It also comes in an injectable form that can only be administered by a healthcare provider.

- Advertisement -

Fluconazole oral tablet is obtainable as both a generic and a brand-name drug. Brand name: Diflucan, which is an oral tablet, is used to treat and prevent a fungal disease called candidiasis. Generic drugs usually cost less than the brand-name version.

In some circumstances, they may not be obtainable in all strengths or forms as the brand-name drug. It can also be used to treat meningitis, which is an infection of the brain or spinal cord, or both.

Uses of Fluconazole

Fluconazole is used to treat and prevent candidiasis. This disease can be caused by infection with one of the many categories of the fungus Candida.

Examples of candidiasis include vaginal yeast infection, as well as thrush (oral yeast infection). Candidiasis can furthermore cause infections on other parts of your body, which includes the: Blood, esophagus, lungs, and even the throat.

People who have undergone bone marrow transplants may be treated with fluconazole to prevent future occurrence of candidiasis.

This is because their immune systems are usually depleted, which can make them susceptible to a severe form of candidiasis. Fluconazole is also used to treat an infection of the brain and spinal cord called meningitis that’s caused by the fungus Cryptococcus.

This drug works by preventing the fungi Candida and Cryptococcus to reproduce. For people with infections from these fungi, this drug helps to get rid of the infection. For people at higher risk of candidiasis, it helps to prevent disease.

Fluconazole belongs to a category of drugs called triazole antifungals. ( A class of drugs is a group of medications that work in a related way. These drugs are mostly to treat identical conditions)

Important warnings

  • This drug can cause one to develop liver failure. The doctor may check the liver function with blood tests while taking this drug. Although, it’s usually reversible once one stops taking it.
  • This drug can also cause a severe rash that can lead to death. One should stop taking the medication if one develops any rashes.
  • This drug can change how the heartbeats, which consequently puts one at risk of a heart rhythm condition called torsades de pointed.

The risk of heart rhythm problems is higher if a person is born with a certain heart rhythm condition, where one has a low potassium level, or one take antipsychotic drugs or certain antidepressants.

- Advertisement -

Fluconazole side effects

Fluconazole isn’t recognized to induce drowsiness, but it can result in other side effects.

Common side effects

The most common side effects of fluconazole oral tablets depend on how much of the drug one needs to take. These side effects can include:

  • Severe rash
  • Stomach pain
  • Headache
  • Vomiting 
  • Diarrhea
  • Nausea or upset stomach
  • Dizziness
  • Changes in the way food tastes

If these effects are not severe, they may go away within a few days or weeks. If they are severe or don’t go away, it’s advisable to consult a doctor or pharmacist.

Severe side effects

Liver damage

Symptoms can include:

  • Yellowing of your skin or the whites of your eyes
  • Dark urine
  • Light-colored stools
  • Severe skin itching
  • Vomiting or nausea

Severe rash in people with acquired Cancer or immunodeficiency syndrome (AIDS)  Symptoms can include:

Torsades de pointes Symptoms can include:

  • Feeling like your heart is skipping a beat (palpitations)
  • Fast, irregular heart rate
  • Dizziness
  • Fainting
  • Seizures

Interactions with other drugs

Fluconazole may interact with other medications. An interaction is when a substance changes the way a drug works.

Fluconazole oral tablets can interact with other medicines, vitamins, or herbs one might be taking. This can be detrimental or can even prevent the drug from working well.

To avoid interactions, the doctor will prescribe or manage all medications carefully. A patient should inform the doctor about all medicines, vitamins, or herbs they are taking. Particular drugs shouldn’t be taken with fluconazole.

When used with fluconazole, these drugs can have harmful effects on the body. Varieties of drugs that can cause interactions with fluconazole are listed below.

- Advertisement -

Drugs that can interact with fluconazole

When 400mg or a higher dose of Terfenadine

It is used with fluconazole; this drug can cause a heart rhythm condition called torsades de pointes, which is a life-threatening situation.

The use of Quinidine, Pimozide, clarithromycin, erythromycin, voriconazole, ranolazine, lomitapide, or donepezil with Fluconazole can also cause this life-threatening heart rhythm condition called torsades de pointes.

Drugs that increase the risk of side effects

Taking fluconazole with certain drugs elevates the risk of side effects from the drugs mentioned below :

  • Diabetes medications, such as glipizide and glyburide. This increased side effects can include low blood sugar, which can cause symptoms such as hunger, dizziness, fast pulse, sweating and chills, and shakiness. 
  • Warfarin also which can cause increased side effects like bruising, blood in urine or stools nosebleeds.
  • Taking Phenytoin with fluconazole can cause confusion, slurred speech, and trouble with coordination. The doctor will measure blood levels of phenytoin while one is taking fluconazole. 
  • Cyclosporine, tacrolimus, and sirolimus can increase side effects, which can include kidney damage. The doctor should check the blood for signs of kidney damage while taking fluconazole. If one shows signs of kidney damage, the doctor may lower the doses of these drugs or stop them entirely until treatment with fluconazole is done.
  • Taking Theophylline drug with fluconazole can cause headaches, seizures, low blood pressure, and muscle cramps. 
  • Zidovudine can increase side effects such as Nausea, vomiting headache, tiredness, loss of appetite, etc
  • Pain medications, such as fentanyl and methadone. The levels of effect of these drugs may be heightened in the body when taken with fluconazole, which can increase side effects like slowed breathing, confusion, and drowsiness.
  • Carbamazepine can increase side effects which can include low blood cell counts, severe rash, heart failure, liver failure, nausea, vomiting, and unsteadiness, 
  • Specific calcium channel blockers, such as felodipine, verapamil, nifedipine, and can when used with fluconazole, can increase side effects include low blood pressure, dizziness, confusion, and headache.
  • Certain statins, such as atorvastatin and simvastatin when use alongside fluconazole can increase side effects, which include muscle pain and weakness and raised levels of creatinine in your blood.
  • Antipsychotic drugs, such as chlorpromazine, haloperidol, and ziprasidone when taken with fluconazole, raise the risk of developing a life-threatening like irregular heart rhythm condition called torsades de pointes.
  • Antidepressants, such as citalopram, escitalopram, and paroxetine, when fluconazole with these medications raises the risk of developing an irregular heart rhythm condition called torsades de pointes.
  • Taking Heart rhythm drugs, such as amiodarone and dofetilide with fluconazole with these medications raises your risk of a one developing a life-threatening irregular heart rhythm condition called torsades de pointes.

Fluconazole warnings

Fluconazole oral tablet comes with numerous signs which can be : 

Allergy warning

This drug can induce a severe allergic reaction. Symptoms can include:

  • Wheezing
  • The throbbing of the heart or ears
  • Swelling of the face, mouth, neck eyelids, or any other part of your body
  • Fever
  • Chills
  • Skin rash, hives, blisters or skin peeling
  • Shortness of breath
  • Coughing

This drug shouldn’t be taken if one has suffered an allergic reaction to it previously, as retaking it could be fatal ( and can cause death even).

Warnings for people with specific health conditions

  • For people with kidney disease: Persons suffering from kidney disease or with a history of kidney disease, shouldn’t take this drug as the kidneys may be unable to excrete this drug from the body as they should and an increase in the amount of fluconazole in the body, cause more side effects. This drug can also make existing kidney disorders worse.
  • People with liver problems: Fluconazole can cause liver problems, and one should consult one’s healthcare provider before taking this drug, especially when one already has a preexisting liver problem.
  • People with high blood sugar levels: The oral suspension form of this drug contains sucrose, which is a kind of sugar. One shouldn’t use this form of fluconazole if one has a blood sugar level related condition and a doctor should be consulted before using this drug
  • People with abnormal heart rhythms: Using fluconazole can affect the heart rhythm. If one already has an abnormal heart rhythm, taking fluconazole may increase the risk of heart rhythm problems.
  • Persons who have certain conditions that lower body immunity, such as cancer, human immunodeficiency virus infection (HIV), or acquired immunodeficiency syndrome (AIDS), are very likely to get a rash from fluconazole. The doctor should monitor the skin for a rash or peeling.

Warnings for other groups

  • Pregnant women: Studies in humans have indicated adverse effects on the fetus when a mother takes this drug in doses of 150 mg or larger doses. There hasn’t been enough research done to ascertain how lower doses of the drug might affect the human fetus.
  • This drug should only be administered during pregnancy in severe cases where it’s needed to treat a dangerous infection in the mother. And it should only be used if the potential risk to the fetus is logical, given the drug’s potential benefit.
    One should talk to the doctor if pregnant or planning to become pregnant and should ask the doctor about the specific harm that may be done to the fetus.
  • Fluconazole can pass into breast milk and may cause side effects in a child who is breastfed with this fluconazole infected milk. A nursing mother should consult a doctor before taking these drugs, As she may need to decide whether to stop breastfeeding or stop taking this drug.
  • For seniors as the kidneys of older adults may not work as well as they used to. This can cause the body to process drugs slowly. Consequently, more of the drug is likely to remain in the body for a longer duration. This can raise the risk of side effects.
  • For children: Fluconazole medication in any form shouldn’t be used in people younger than six months.

How to take fluconazole?

This dosage information is for a fluconazole oral tablet

  • Generic: Fluconazole
  • Form: Oral tablet
  • Strengths: 50 mg, 100 mg, 150 mg, 200 mg
  • Brand: Diflucan
  • Form: Oral tablet
  • Strengths: 50 mg, 100 mg, 150 mg, 200 mg

Dosage for vaginal candidiasis

  • Adult dosage (ages 18–64 years)
  • Typical dosage: One 150-mg dose.
  • Child dosage (ages 6months – 17 years)

The use of this drug hasn’t been approved in children younger than 18 years.

Senior dosage (ages 65 years and older)

For seniors as the kidneys of older adults may not work as well as they used to. This can cause the body to process drugs slowly. Consequently, more of the drug is likely to remain in the body for a longer duration. This can raise the risk of side effects.

The doctor may prescribe for one to start on a lowered dose or a different dosing schedule. To help keep levels of this drug from building up too much in the body.

- Advertisement -

Dosage for nonvaginal candidiasis

Adult dosage (ages 18–64 years)

  • Typical dosage: Depending on the type of infection you have, your daily dose could be between 50 mg and 400 mg.
  • Treatment length: Treatment can last up to several weeks.

Child dosage (ages six months through 17 years)

  • Typical dosage: Dosage depends on the weight of the child taking the drug, and the type of infection being treated.
  • Treatment length: The length of treatment depends on the infection being treated.
    Child dosage (ages 0–5 months)

Although the use of this drug isn’t recommended in infants younger than six months.

Senior dosage (ages 65 years and older)

For seniors as the kidneys of older adults may not work as well as they used to. This can cause the body to process drugs slowly. Consequently, more of the drug is likely to remain in the body for a longer duration.

This can raise the risk of side effects. The doctor may prescribe for one to start on a lowered dose or a different dosing schedule. To help keep levels of this drug from building up too much in the body.

Dosage for candidiasis prevention

Adult dosage (ages 18–64 years)

  • Typical dosage: 400 mg, taken once per day.
  • Treatment length: Treatment can last several weeks.

Child dosage (ages 0–17 years)

The use of this drug for the prevention of candidiasis in people younger than 18 years hasn’t been approved.

Senior dosage (ages 65 years and older)

For seniors as the kidneys of older adults may not work as well as they used to. This can cause the body to process drugs slowly. Consequently, more of the drug is likely to remain in the body for a longer duration. This can raise the risk of side effects.

The doctor may prescribe for one to start on a lowered dose or a different dosing schedule. To help keep levels of this drug from building up too much in the body.

Dosage for cryptococcal meningitis

Adult dosage (ages 18–64 years)

  • Typical dosage: 400 mg on the first day. The dose from day two on is usually 200–400 mg, taken once per day.
  • Treatment length: Treatment typically lasts 10–12 weeks after a test called a cerebrospinal fluid culture no longer detects bacteria.

Child dosage (ages six months through 17 years)

Dosage for children is based on weight.

  • Typical dosage: On the first day, your child will take 12 mg per kilogram of body weight. The dose from day 2 is usually 6–12 mg per kilogram, taken once per day.
  • Treatment length: Treatment typically lasts 10–12 weeks after a test called a cerebrospinal fluid culture no longer detects bacteria.

Child dosage (ages 0–5 months)

The use of this drug isn’t recommended in infants younger than six months.

- Advertisement -

Senior dosage (ages 65 years and older)

For seniors as the kidneys of older adults may not work as well as they used to. This can cause the body to process drugs slowly. Consequently, more of the drug is likely to remain in the body for a longer duration.

This can raise the risk of side effects. The doctor may prescribe for one to start on a lowered dose or a different dosing schedule. To help keep levels of this drug from building up too much in the body.

Special dosage considerations

  • For people with kidney disease who are supposed to take more than a single dose of fluconazole, the dose may be lowered. The doctor may give the first dose of 50–400 mg, with additional doses that range between that amount and half of that amount, based on the kidney function.

Directions for use

Fluconazole oral tablets are used for both short-term and long-term treatment. It comes with risks if one doesn’t take it as prescribed.

If one stops taking the drug suddenly or doesn’t take it at all: Your infection may not get better or may get worse.

If one misses doses or doesn’t take the drug on schedule: the medication may not work as well or may stop working altogether. For this drug to work well, a certain amount needs to be in your body at all times.

If one takes too much: they could have dangerous levels of the drug in your body. Symptoms of an overdose of this drug can include:

  • Hallucinations
  • Paranoia
  • Abnormal heart rhythm
  • Blue tint to your skin
  • Decreased breathing

What to do if you miss a dose?

The person should take the dose as soon as they remember. But if one remembers just a few hours before the next scheduled dose, take only one treatment, although they shouldn’t try to catch up by taking two doses at once.

This could result in dangerous side effects. The drugs are considered to be active and working when on notice decreased symptoms of infection.

Important considerations for taking fluconazole

These considerations should be kept in mind if a doctor prescribes a fluconazole oral tablet for a person 

General

  • One can take fluconazole with or without food.
  • One can also cut or crush the tablet.

Storage

  • Store fluconazole tablets below 86°F (30°C).
  • This medication shouldn’t be stored in moist or damp areas, such as bathrooms.

Refills

A prescription for this medication is refillable. One should not need a new prescription for this medication to be refilled. As the doctor will write the number of refills authorized on your prescription.

- Advertisement -

Travel

When traveling with medication:

  • Always carry your medication at all times. -When flying, never put it into a checked bag.
  • Keep it in your carry-on bag.
  • Don’t worry about airport X-ray machines. -They can’t hurt your medication.
  • There may be a need to show airport staff the pharmacy label for the medicine. One should always carry the original prescription-labeled box while traveling 
  • Never put this medication in your car’s glove compartment or leave it in the car. Be sure to avoid doing this when the weather is very hot or very cold.

Clinical monitoring

The doctor should monitor the kidneys and liver function while taking this drug. The doctor should have blood tests done to check how well the liver and kidneys are functioning.

If these organs aren’t working well, the doctor may decide to lower the dosage or instruction one to stop taking this drug.

Are there any alternatives to fluconazole?

There are other drugs attainable to treat whatever condition fluconazole can be used for, although some may be better suited or efficient for some disorders than others. The patient should talk to the doctor about other drug options that may work better for the patient. Remember to check in with your doctor as always.

Jennifer Aigbini
I am a language enthusiast, studying Linguistics at the University of Benin, in Nigeria.