Clarithromycin belongs to the group of medications called macrolide antibiotics. It is used to treat infections caused by certain bacteria. It works by killing or stopping the growth of bacteria that can cause certain infections. Clarithromycin may be prescribed for people with bacterial throat infections, sinus infections, ear infections, bronchitis, pneumonia, and skin infections such as impetigo and cellulitis.

Clarithromycin may also be used to prevent and treat certain infections (mycobacterium avium complex or MAC), associated with human immunodeficiency virus (HIV) infection. Clarithromycin can be used in combination with other medications to kill H. pylori, a bacteria known to cause ulcers in the digestive tract.

This medication may be available under multiple brand names and/or in several different forms. Any specific brand name of this medication may not be available in all of the forms or approved for all of the conditions discussed here. As well, some forms of this medication may not be used for all of the conditions discussed here.

Your doctor may have suggested this medication for conditions other than those listed in these drug information articles. If you have not discussed this with your doctor or are not sure why you are taking this medication, speak to your doctor. Do not stop taking this medication without consulting your doctor.

Do not give this medication to anyone else, even if they have the same symptoms as you do. It can be harmful for people to take this medication if their doctor has not prescribed it.

Adults: The recommended adult dose of clarithromycin tablets is 250 mg to 500 mg twice daily (every 12 hours) for 7 to 14 days, depending on the condition being treated.

The recommended adult dose of the extended-release form of clarithromycin is 1,000 mg (2 tablets) once daily for 5 to 14 days, depending on the condition being treated.

For the treatment and prevention of MAC, the usual dose of clarithromycin is 500 mg twice daily. When used with other medications to kill H. pylori, the usual dose of clarithromycin is 500 mg twice daily for 10 days.

Children: The recommended total daily dose for children is 15 mg per kilogram of body weight (to a maximum of 1,000 mg per day). This total daily dose should be divided in 2 equal doses given 12 hours apart. Total treatment duration is usually 5 to 10 days, depending on the condition being treated. For the treatment and prevention of MAC, the usual dose of clarithromycin is 7.5 mg per kilogram of body weight twice daily (up to 500 mg twice daily).

If the child is receiving an oral suspension of clarithromycin, use an oral syringe to measure each dose of the liquid, as it gives a more accurate measurement than household teaspoons.

Clarithromycin tablets and clarithromycin suspension (given twice daily) may be taken with or without food. Taking this medication with food may cause less stomach upset.

The extended-release tablets of clarithromycin must be taken with food. The tablets must be swallowed whole and not crushed or broken.

Finish all of this medication, even if you have started to feel better.

Many things can affect the dose of medication that a person needs, such as body weight, other medical conditions, and other medications. If your doctor has recommended a dose different from the ones listed here, do not change the way that you are taking the medication without consulting your doctor.

It is important to take this medication exactly as prescribed by your doctor. If you miss a dose, take it as soon as possible and continue with your regular schedule. If it is almost time for your next dose, skip the missed dose and continue with your regular dosing schedule. Do not take a double dose to make up for a missed one. If you are not sure what to do after missing a dose, contact your doctor or pharmacist for advice.

Store clarithromycin tablets at room temperature, protect them from light and moisture, and keep them out of the reach of children.

Store clarithromycin oral suspension at room temperature with the bottle tightly closed and protected from light. Do not refrigerate. Any unused oral suspension should be thrown away after 14 days. Rinse the dose-measuring oral syringe between uses. Do not store the suspension in the syringe.

Do not take clarithromycin if you:

• are allergic to clarithromycin or any ingredients of this medication
• are allergic to other macrolide antibiotics, such as erythromycin or azithromycin
• have had jaundice (yellowing of the skin or eyes) or liver problems associated with taking clarithromycin
• have severe liver failure in addition to decreased kidney function
• have or have had QT prolongation (an abnormal electrical activity of the heart) or an abnormal heart rhythm
• have untreated hypokalemia (low potassium) or hypomagnesemia (low magnesium levels in the blood)
• are taking any of the following medications:
• astemizole
• cisapride
• colchicine
• domperidone
• ergot alkaloids (e.g., dihydroergotamine, ergonovine, ergotamine, methylergonovine)
• oral midazolam
• lomitapide
• pimozide
• saquinavir
• "statin" cholesterol lowering medications (e.g., lovastatin, simvastatin)
• terfenadine
• ticagrelor

Many medications can cause side effects. A side effect is an unwanted response to a medication when it is taken in normal doses. Side effects can be mild or severe, temporary or permanent.

The side effects listed below are not experienced by everyone who takes this medication. If you are concerned about side effects, discuss the risks and benefits of this medication with your doctor.

The following side effects have been reported by at least 1% of people taking this medication. Many of these side effects can be managed, and some may go away on their own over time.

Contact your doctor if you experience these side effects and they are severe or bothersome. Your pharmacist may be able to advise you on managing side effects.

• abdominal pain
• change in sense of taste
• diarrhea (mild)
• dizziness
• gas
• headache
• hearing trouble
• heartburn
• nausea
• ringing in the ears
• vomiting

Although most of the side effects listed below don't happen very often, they could lead to serious problems if you do not seek medical attention.

Check with your doctor as soon as possible if any of the following side effects occur:

• severe abdominal or stomach cramps and pain
• skin rash
• symptoms of liver problems (e.g., abdominal tenderness, yellow eyes or skin, skin rash, itching, dark urine)
• symptoms of myasthenia gravis (e.g., muscle weakness, drooping eyelid, vision changes, difficulty chewing and swallowing, trouble breathing)
• watery and severe diarrhea, which may also be bloody

Stop taking the medication and seek immediate medical attention if any of the following occur:

• abnormal or irregular heartbeat
• symptoms of a severe allergic reaction (e.g., hives; difficulty breathing; sore throat; or swelling of the face, mouth, throat, or tongue)
• symptoms of a severe skin reaction (e.g., peeling or blistering skin)

Some people may experience side effects other than those listed. Check with your doctor if you notice any symptom that worries you while you are taking this medication.

Before you begin using a medication, be sure to inform your doctor of any medical conditions or allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use this medication.

Abnormal heart rhythm: Clarithromycin may cause a heart rhythm problem called QT prolongation. If you have a history of QT prolongation, a medical condition associated with QT prolongation, or are taking certain medications (e.g., amiodarone, sotalol), discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Allergy: If you have had some form of allergy to erythromycin or azithromycin, you may be more likely to have an allergic reaction to this medication. If you develop symptoms of an allergic reaction such as a rash, contact your doctor. If you develop hives; difficulty breathing; or swelling of the face, mouth, throat, or tongue, stop taking this medication and get immediate medical attention.

Bacterial resistance: Misuse of an antibiotic such as clarithromycin may lead to the growth of resistant bacteria that will not be killed by the antibiotic. If this happens, the antibiotic may not work for you in the future. Although you may begin to feel better when you first start taking clarithromycin, you need to continue taking the medication, exactly as prescribed by your doctor, to finish ridding your body of the infection and to prevent resistant bacteria from taking hold. Do not take clarithromycin or other antibiotics to treat a viral infection such as the common cold; antibiotics do not kill viruses, and using them to treat viral infections can lead to the growth of resistant bacteria.

Diarrhea: As with other antibiotics, clarithromycin is associated with a serious infection called Clostridium difficile-associated diarrhea, caused by the bacteria C. difficile. This can occur as late as 2 months after your last dose of this medication.

If you have loose, watery bowel movements especially if they are green, foul-smelling, or bloody and accompanied by fever, either during or after taking clarithromycin, get medical attention as soon as possible.

Dizziness, confusion, and disorientation: This medication can cause dizziness, confusion, or disorientation. Do not drive or operate machinery until you are certain that this medication does not affect your ability to perform these tasks safely.

Kidney function: Kidney disease or reduced kidney function may cause this medication to build up in the body, causing side effects. If you have reduced kidney function, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Liver problems: Liver disease or reduced liver function may cause this medication to build up in the body, causing side effects. If you have reduced liver function, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed. This medication should not be used by people with severe liver problems.

If you develop symptoms of liver problems (e.g., loss of appetite, nausea, vomiting, yellowing of the skin or eyes, dark urine, itchy skin, abdominal pain), contact your doctor immediately.

Myasthenia gravis: This medication can worsen or cause symptoms of myasthenia gravis. If your symptoms worsen or you develop new symptoms such as double vision, drooping eyelids, muscle weakness, or difficulty chewing or swallowing, contact your doctor.

Pregnancy: Clarithromycin should not be used during pregnancy, especially the first 3 months of pregnancy, unless there is no other appropriate therapy. If you become pregnant while taking this medication, contact your doctor.

Breast-feeding: This medication passes into breast milk. If you are a breast-feeding mother and are taking clarithromycin, it may affect your baby. Talk to your doctor about whether you should continue breast-feeding.

Children: The safety and effectiveness of using clarithromycin oral suspension have not been established for children younger than 6 months old. For pneumonia, the use of clarithromycin oral suspension has not been studied for children younger than 3 years old. The safety and effectiveness of using clarithromycin to prevent MAC infection has not been studied for children younger than 20 months old. The safety and effectiveness of using clarithromycin tablets have not been established for children younger than 12 years old.

There may be an interaction between clarithromycin and any of the following:

• aliskiren
• almotriptan
• alpha-blockers (e.g., alfuzosin, doxazosin, silodosin, tamsulosin)
• antiarrhythmic medications (e.g., amiodarone, disopyramide, dronedarone, flecainide, lidocaine, procainamide, propafenone, quinidine, sotalol)
• anti-cancer medications (e.g., cabazitaxel, docetaxel, doxorubicin, etoposide, ifosfamide, irinotecan, vincristine)
• anti-emetic medications (serotonin antagonists; e.g., granisetron, ondansetron)
• antipsychotics (e.g., chlorpromazine, clozapine, haloperidol, olanzapine, quetiapine, risperidone)
• apalutamide
• apixaban
• aprepitant
• "azole" antifungals (e.g., itraconazole, ketoconazole, voriconazole)
• bacillus Calmette-Guérin (BCG) vaccine
• benzodiazepines (e.g., clonazepam, diazepam, lorazepam)
• bosentan
• bromocriptine
• buprenorphine
• buspirone
• cabergoline
• calcitriol
• calcium channel blockers (e.g., amlodipine, diltiazem, felodipine, nifedipine, verapamil)
• cannabis
• chloroquine
• cholera vaccine
• cinacalcet
• clindamycin
• cobicistat
• colchicine
• conivaptan
• corticosteroids (e.g., budesonide, dexamethasone, fluticasone, hydrocortisone, prednisone)
• cyclosporine
• dabigatran
• darifenacin
• digoxin
• domperidone
• doxepin
• dutasteride
• edoxaban
• eletriptan
• elexacaftor, tezacaftor, and ivacaftor
• eluxadoline
• enzalutamide
• eplerenone
• ergot alkaloids (e.g., dihydroergotamine, ergonovine, ergotamine, methylergonovine)
• eszopiclone
• estrogens (e.g., conjugated estrogen, estradiol, ethinyl estradiol, norethindrone)
• everolimus
• flibanserin
• galantamine
• grapefruit juice
• guanfacine
• hepatitis C antivirals (e.g., glecaprevir and pibrentasvir, grazoprevir, voxilaprevir)
• HIV non-nucleoside reverse transcriptase inhibitors (NNRTIs; e.g., efavirenz, etravirine, nevirapine, rilpivirine)
• HIV protease inhibitors (e.g., atazanavir, indinavir, ritonavir, saquinavir)
• indacaterol
• insulin
• ivabradine
• lemborexant
• lomitapide
• lumacaftor and ivacaftor
• macitentan
• other macrolide antibiotics (e.g., azithromycin, erythromycin)
• maraviroc
• mefloquine
• methadone
• mifepristone
• mirtazapine
• modafinil
• nadolol
• narcotic pain relievers (e.g., codeine, fentanyl, morphine, oxycodone, tramadol)
• nitrates (e.g., isosorbide dinitrate, isosorbide mononitrate)
• oxybutynin
• pentamidine
• phosphodiesterase 5 inhibitors (e.g., sildenafil, tadalafil, vardenafil)
• praziquantel
• progestins (e.g., dienogest, levonorgestrel, medroxyprogesterone, norethindrone)
• quinine
• quinolone antibiotics (e.g., ciprofloxacin, norfloxacin, ofloxacin)
• repaglinide
• rifabutin
• rifampin
• riociguat
• rivaroxaban
• romidepsin
• rupatadine
• salmeterol
• saxagliptin
• seizure medications (e.g., carbamazepine, divalproex, phenobarbital, phenytoin, rupatadine)
• selective serotonin reuptake inhibitors (SSRIs; e.g., citalopram, escitalopram, fluoxetine, paroxetine, sertraline)
• sirolimus
• sodium picosulfate
• sotalol
• "statin" anti-cholesterol medications (e.g., atorvastatin, lovastatin, simvastatin)
• St. John's wort
• sulfonylureas (e.g., glyburide, glipizide, tolbutamide)
• tacrolimus
• theophyllines (e.g., aminophylline, oxtriphylline, theophylline)
• ticagrelor
• tolterodine
• tolvaptan
• trazodone
• typhoid vaccine
• tyrosine kinase inhibitors (e.g., bosutinib, crizotinib, dabrafenib, dasatinib, imatinib, nilotinib, pazopanib, tofacitinib)
• vilanterol
• warfarin
• zidovudine
• zolpidem
• zopiclone

If you are taking any of these medications, speak with your doctor or pharmacist. Depending on your specific circumstances, your doctor may want you to:

• stop taking one of the medications,
• change one of the medications to another,
• change how you are taking one or both of the medications, or
• leave everything as is.

An interaction between two medications does not always mean that you must stop taking one of them. Speak to your doctor about how any drug interactions are being managed or should be managed.

Medications other than the ones listed above may interact with this medication. Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications that you are taking. Also tell them about any supplements you take. Since caffeine, alcohol, the nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them.