clarithromycin
Brand names: Biaxin
Clarithromycin is an antibiotic that fights bacterial infections. It belongs to a class of drugs called macrolides.
Drug Pricing (NADAC)
Generic Price
$0.92/unit
Generic Available
Yes (9 manufacturers)
Pricing data from NADAC (CMS), effective December 18, 2024. Compare all drug costs →
What it does
Clarithromycin treats mild to moderate infections caused by certain bacteria.
Common side effects
Abdominal pain, Diarrhea, Nausea
Key warnings
Clarithromycin can cause severe allergic reactions.
How It Works
Clarithromycin works by stopping the growth of bacteria. It prevents bacteria from making proteins they need to survive. This helps your body fight off the infection.
How to Take It
Take clarithromycin tablets as your doctor tells you. You can take it with or without food. The usual dose for adults is 250 mg or 500 mg every 12 hours for 7 to 14 days. For children, the dose is usually 15 mg/kg/day divided every 12 hours for 10 days.
Pregnancy & Breastfeeding
Clarithromycin is not recommended during pregnancy unless there are no other options. Talk to your doctor if you are pregnant or plan to become pregnant. It is not known if clarithromycin passes into breast milk, so talk to your doctor before breastfeeding.
Missed Dose
If you miss a dose, take it as soon as you remember. If it is almost time for your next dose, skip the missed dose and continue with your regular schedule.
Storage
Store clarithromycin tablets at room temperature (68° to 77°F) in a tightly closed container, protected from light.
Side Effects (from patient reports)
Based on 19,300 FDA adverse event reports.
FDA Adverse Event Report Analysis
Detailed analysis of 33,247 reports from the FDA Adverse Event Reporting System (FAERS). Reports span 1999–2025.
Total Reports
33,247
Death-Related Reports
2,888
Hospitalization Reports
13,190
Top Indication
Product Used For Unknown Indication
Gender Distribution
Age Distribution
Most Reported Adverse Reactions (FAERS)
| # | Reaction | Reports |
|---|---|---|
| 1 | DRUG INTERACTION | 2,906 |
| 2 | DRUG INEFFECTIVE | 2,476 |
| 3 | NAUSEA | 2,214 |
| 4 | DYSPNOEA | 1,959 |
| 5 | DIARRHOEA | 1,937 |
| 6 | MALAISE | 1,650 |
| 7 | PYREXIA | 1,631 |
| 8 | OFF LABEL USE | 1,533 |
| 9 | HEADACHE | 1,518 |
| 10 | VOMITING | 1,476 |
| 11 | RASH | 1,250 |
| 12 | PNEUMONIA | 1,228 |
| 13 | DIZZINESS | 1,168 |
| 14 | FATIGUE | 1,146 |
| 15 | ABDOMINAL PAIN | 1,015 |
Reactions in Death Reports
Reactions in Hospitalization Reports
Source: FDA FAERS (Adverse Event Reporting System) FDA FAERS (Adverse Event Reporting System) Reports are voluntary and do not establish causation
Serious Warnings
Clarithromycin can cause severe allergic reactions. Stop taking it and get medical help right away if you have signs of a reaction. This medicine can also cause heart rhythm problems (QT prolongation) and liver problems. Tell your doctor if you have heart or liver issues. Clarithromycin may increase the risk of death in patients with coronary artery disease.
Known Drug Interactions
Colchicine (in patients with normal renal and hepatic function) Use With Caution Antipsychotics: Pimozide Contraindicated Pimozide: [See Contraindications ( 4.2 )] Quetiapine Lurasidone Quetiapine: Quetiapine is a substrate for CYP3A4, which is inhibited by clarithromycin. Co‑administration with clarithromycin could result in increased quetiapine exposure and possible quetiapine related toxicities. Refer to quetiapine prescribing information for recommendations on dose reduction if co‑administered with CYP3A4 inhibitors such as clarithromycin.
Mechanism: Clarithromycin stops your body from breaking down quetiapine, which can cause the drug to build up to toxic levels.
What to do: Your doctor may need to lower your quetiapine dose while you are taking this antibiotic.
Gastroprokinetic Agents: Cisapride Contraindicated Cisapride: [See Contraindications ( 4.2 )] Lipid-lowering agents: Lomitapide Lovastatin Simvastatin Contraindicated Lomitapide, Lovastatin, Simvastatin: Clarithromycin may increase the exposure of these drugs by inhibition of CYP3A metabolism, thereby increasing the risk of toxicities from these drugs [see Contraindications ( 4.5 ) and Warnings and Precautions ( 5.4 )] Atorvastatin, Pravastatin, Fluvastatin: [See Warnings and Precautions ( 5.4 )] Atorvastatin Pravastatin Use With Caution Fluvastatin No Dose Adjustment Hypoglycemic Agents: N...
Mechanism: Clarithromycin can interfere with how your body handles certain diabetes drugs, which may increase the risk of your blood sugar falling too low.
What to do: Watch your blood sugar levels carefully and consult your doctor for any needed dose adjustments.
Fluconazole No Dose Adjustment Fluconazole: [see Pharmacokinetics ( 12.3 )] Anti-Gout Agents: Colchicine (in patients with renal or hepatic impairment) Contraindicated Colchicine: Colchicine is a substrate for both CYP3A and the efflux transporter, P-glycoprotein (Pgp).
Mechanism: These two drugs do not significantly affect each other's levels in the body.
What to do: No dose adjustments are necessary when taking these medications at the same time.
Gastroprokinetic Agents: Cisapride Contraindicated Cisapride: [See Contraindications ( 4.2 )] Lipid-lowering agents: Lomitapide Lovastatin Simvastatin Contraindicated Lomitapide, Lovastatin, Simvastatin: Clarithromycin may increase the exposure of these drugs by inhibition of CYP3A metabolism, thereby increasing the risk of toxicities from these drugs [see Contraindications ( 4.5 ) and Warnings and Precautions ( 5.4 )] Atorvastatin, Pravastatin, Fluvastatin: [See Warnings and Precautions ( 5.4 )] Atorvastatin Pravastatin Use With Caution Fluvastatin No Dose Adjustment Hypoglycemic Agents: N...
Mechanism: Clarithromycin blocks the liver enzyme that breaks down cyclosporine, which causes the drug to build up in your body.
What to do: Your doctor should monitor your blood levels closely and may need to adjust your dose while you are taking the antibiotic.
Colchicine (in patients with normal renal and hepatic function) Use With Caution Antipsychotics: Pimozide Contraindicated Pimozide: [See Contraindications ( 4.2 )] Quetiapine Lurasidone Quetiapine: Quetiapine is a substrate for CYP3A4, which is inhibited by clarithromycin. Lurasidone: [See Contraindications ( 4.7 )] Antispasmodics: Tolterodine (patients deficient in CYP2D6 activity) Use With Caution Tolterodine: The primary route of metabolism for tolterodine is via CYP2D6.
Mechanism: Clarithromycin stops the body from clearing lurasidone by blocking a specific enzyme, which can lead to toxic levels of the medication.
What to do: Avoid taking these two drugs together as this combination is not recommended by the FDA.
Common Questions
Can I take clarithromycin if I'm allergic to penicillin?
Can I drink alcohol while taking clarithromycin?
Will clarithromycin interact with my other medications?
How long does it take for clarithromycin to start working?
What should I do if I get diarrhea while taking clarithromycin?
Can clarithromycin cause a yeast infection?
Is it okay to stop taking clarithromycin when I feel better?
Does clarithromycin cause sun sensitivity?
What if I have kidney problems?
Can clarithromycin affect my heart?
What are the common side effects of clarithromycin?
Does clarithromycin interact with other medications?
What drug class is clarithromycin?
Is clarithromycin safe during pregnancy?
Related Medications in Macrolide Antibiotic
Other drugs grouped near clarithromycin — same-class peers and common alternatives.
amikacin
Amikin
Amikacin is an antibiotic medicine.
Compare with clarithromycin →
amoxicillin
Amoxil
Amoxicillin and Clavulanate Potassium is a combination medicine used to fight bacterial infections.
Compare with clarithromycin →
amoxicillin/clavulanate
Augmentin
Augmentin is a combination of two medicines, amoxicillin and clavulanate.
Compare with clarithromycin →
ampicillin/sulbactam
Unasyn
Unasyn is a combination of two antibiotics that fights bacteria in your body.
Compare with clarithromycin →
azithromycin
Zithromax, Z-Pack
Azithromycin is an antibiotic that fights bacteria.
Compare with clarithromycin →
Medication Guides
Understanding Drug Interactions
How CYP450 enzymes, inhibitors, and inducers affect your medications
Generic vs Brand Name Drugs
FDA requirements, cost savings, and when the difference matters
Narrow Therapeutic Index Drugs
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Common Drug Interactions
Dangerous medication combinations and how to protect yourself
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What the FDA Data Shows for clarithromycin
The FDA label for clarithromycin (sold under brand names such as Biaxin) classifies it as a prescription-only medication in the Macrolide Antibiotic class. Clarithromycin treats mild to moderate infections caused by certain bacteria. Official labeling lists 5 commonly reported side effects, including Abdominal pain, Diarrhea, Nausea.
Post-market surveillance from the FDA Adverse Event Reporting System (FAERS) captures real-world experience. For this drug, FAERS contains 19,300 voluntary reports. The database also lists 81 documented drug interactions derived from FDA labeling, with the top-flagged interaction rated major severity. NADAC pricing from CMS shows a generic unit cost of $0.92.
Report counts do not establish causation — a FAERS entry documents a temporal association, not proof that the drug produced the outcome. Widely prescribed medications naturally accumulate more reports than niche therapies, so raw totals must be interpreted alongside total exposure. Shortage status, recall history, and patent information further shape supply and switching decisions. This page summarizes public FDA data for educational purposes only and is not a substitute for professional medical advice — always consult a licensed healthcare provider before starting, stopping, or changing any medication.
Data Sources
Drug labeling: FDA Drug Labels (SPL/DailyMed). Adverse events: FDA Adverse Event Reporting System (FAERS). Pricing: CMS National Average Drug Acquisition Cost (NADAC).
FAERS reports are voluntary and do not establish causation. Drug interactions are derived from FDA labeling and clinical references. Always consult a healthcare professional before making medication decisions.
Last updated: October 15, 2025
Read our methodology — how this data is sourced, computed, and verified.
All federal data sources used on this page
- FDA Orange Book — approved drug products with therapeutic equivalence. accessdata.fda.gov/cder/ob
- FDA DailyMed — NIH-hosted drug labeling for FDA-approved meds. dailymed.nlm.nih.gov
- FDA Adverse Event Reporting System (FAERS) — post-marketing safety surveillance. fda.gov/drugs/faers
- NLM RxNorm — standardized clinical drug nomenclature. nlm.nih.gov/research/umls/rxnorm
- CMS Medicare Part B Drug Average Sales Price Files — federal drug pricing data. cms.gov/medicare/part-b-drugs/asp
- FDA Drug Shortages Database — current and resolved drug shortage tracking. accessdata.fda.gov/drugshortages