Clarithromycin (Clarothromycin) – Patient Information (Australia)

Clarithromycin is a widely used antibiotic in the macrolide family. It is commonly prescribed to treat certain bacterial infections of the upper and lower respiratory tract, as well as some skin infections and infections related to Helicobacter pylori when used in combination with other medicines. This guide is written to be patient-friendly and practical, with information about how clarithromycin works, how it behaves in the body, typical uses, timing, interactions, and important safety considerations.

If you have specific questions about your infection or course, speak with a pharmacist or doctor. Antibiotics should be used only for the condition they are intended for.

Basic product information

• Medicine name: Clarithromycin
• Type: Antibiotic (macrolide)
• Common forms: Tablets and oral suspension (brands and strengths may vary)
• Usual dosing frequency: Often 2 times daily (based on the indication)
• Where it is used: Treatment of selected bacterial infections and combination therapy for H. pylori

In Australia, product brands and pack sizes vary. Your pharmacist can provide the specific strength and instructions for the exact product you receive.

How clarithromycin works (mechanism of action)

Clarithromycin works by interfering with bacterial protein production. Specifically, it binds to the 50S ribosomal subunit of susceptible bacteria, which helps stop the bacteria from making the proteins they need to grow and multiply. This action can be bacteriostatic (slows growth) for some organisms and bactericidal (kills) for others, depending on the bacteria and drug concentration.

Clarithromycin also has anti-inflammatory properties that may contribute to symptom improvement in certain respiratory infections.

Pharmacokinetics (how the body handles clarithromycin)

“Pharmacokinetics” describes what the body does with the medicine—how it is absorbed, distributed, metabolised, and eliminated. Understanding this helps explain timing, dosing, and why interactions matter.

• Absorption: Clarithromycin is absorbed through the gastrointestinal tract. Food may alter absorption, but it usually does not prevent it from working.
• Metabolism: It is metabolised in the liver. A key metabolite is 14-hydroxyclarithromycin, which also has antibacterial activity.
• Distribution: It distributes into many tissues, including respiratory tissues. Some effect persists after doses due to tissue penetration.
• Elimination: The medicine and its metabolites are cleared from the body via the liver and kidneys.
• Half-life: The half-life varies with formulation and dosing. With standard dosing, levels may be lower as the course continues, which is why a regular schedule is important.

Kidney or liver impairment can change drug levels. Your doctor or pharmacist may adjust dosing or choose an alternative if necessary.

Typical use and indications

Clarithromycin is used for bacterial infections caused by organisms that are susceptible. It is not effective for viral illnesses such as the common cold or flu. Your prescriber will consider the likely cause of infection, local resistance patterns, your health history, and possible interactions with other medicines.

Common indications include:

• Respiratory tract infections
  • Some cases of acute bacterial sinusitis
  • Exacerbations of chronic bronchitis
  • Community-acquired pneumonia (in selected situations)
  • Other specified upper respiratory tract infections, depending on susceptibility and guidelines
• Skin and soft tissue infections (in selected cases)
• Mycobacterial infections (in particular settings, often under specialist guidance)
• Helicobacter pylori eradication therapy as part of combination treatment

For H. pylori, clarithromycin is typically used with other medicines (commonly including acid suppression and additional antibiotics) to maximise eradication rates. Because resistance to clarithromycin in H. pylori varies, local and guideline-based regimens are important.

Dosing: how much and how long

Dosing depends on the infection type, severity, your age and weight (especially for children if applicable), kidney and liver function, and the combination regimen used. Below are general examples of typical dosing patterns. Always follow the instructions provided with your specific product.

Missed dose: Take it as soon as you remember. If it is close to the next dose, skip the missed dose—do not double up. If you are unsure, ask your pharmacist.

Finish the course: Even if you feel better, do not stop early. Stopping early can increase the chance that bacteria survive and become resistant.

Timing: when to take clarithromycin

• Twice daily schedules: Try to take doses roughly 12 hours apart (for example, morning and evening).
• Once daily or other schedules: Follow the exact instructions on your product label.
• With food: Many patients take clarithromycin with or after food to reduce stomach upset. If your specific product label advises a fasting schedule, follow that advice.

If you experience nausea, taking clarithromycin with a meal (unless your instructions say otherwise) can help.

Food interactions

Food can influence how much clarithromycin is absorbed. In many cases, taking it with food may reduce stomach discomfort. However, some formulations may have different recommendations.

• General approach: If your stomach is sensitive, taking clarithromycin with food can improve tolerability.
• Consistency matters: Try to take it the same way each day (either always with food or always as directed without food).

If you are also taking medicines that must be separated from food (for example, some antacids or certain gastric therapies), ask your pharmacist how to space them.

Alcohol and medicine interactions

Alcohol

Alcohol can worsen side effects such as nausea, stomach upset, dizziness, and can place additional stress on the liver. Clarithromycin is metabolised in the liver, so it is wise to avoid or minimise alcohol while taking the medicine.

If you drink alcohol, consider discussing your individual risk factors (liver disease, other medications, previous side effects) with a pharmacist.

Important medicine interactions (examples)

Clarithromycin can interact with a number of medicines because it affects liver enzymes involved in drug metabolism and can influence heart rhythm. Always tell your pharmacist about all medicines you take, including over-the-counter products and herbal supplements.

• Statins (cholesterol medicines): Clarithromycin can raise statin levels in the blood and increase the risk of muscle-related side effects.
• Some heart rhythm medicines: Certain combinations may increase risk of QT prolongation (a heart rhythm disturbance).
• Anticoagulants (blood thinners): Monitoring may be required with warfarin or similar medicines.
• Diabetes medicines: Blood sugar may be affected; some patients require closer monitoring.
• Other antibiotics: Some combinations may not be needed and can increase side effects.
• Antiepileptic medicines: Drug levels can be affected depending on the medicine.
• Colchicine (especially in certain risk groups): Clarithromycin can increase colchicine exposure; this combination can be risky.
• Ergot derivatives: Risk of serious side effects—avoid unless specifically directed.

Grapefruit / certain fruit juices: While not always a direct rule for clarithromycin, some macrolides are affected by substances in grapefruit. To be safe, avoid grapefruit products unless your pharmacist confirms they are suitable for you.

If you’re unsure whether your other medicines interact with clarithromycin, ask before starting.

Safety profile and side effects

Like all medicines, clarithromycin can cause side effects. Many people experience mild effects that improve as treatment continues. Some side effects require prompt medical attention.

Common side effects

• Diarrhoea
• Nausea or vomiting
• Abdominal discomfort
• Headache
• Changes in taste (metallic taste)
• Thrush or other overgrowth reactions

Less common but important risks

• Allergic reactions: swelling of face/lips, rash, itching, wheezing, trouble breathing. Seek urgent medical help if severe symptoms occur.
• Liver problems: symptoms such as yellowing of skin/eyes (jaundice), dark urine, severe fatigue, or persistent upper abdominal pain.
• Heart rhythm changes: palpitations, dizziness, fainting, or feeling “irregular” heartbeat. This risk can be higher with certain other medicines or existing heart conditions.
• Clostridioides difficile (C. difficile) diarrhoea: watery or bloody diarrhoea, abdominal cramps, and fever. Seek medical advice urgently if this occurs, especially if severe or persistent.

When to get urgent help

Contact emergency services or seek urgent medical assessment if you experience:

• Difficulty breathing, swelling of lips/face, or widespread severe rash
• Fainting, severe dizziness, or severe palpitations
• Severe or persistent diarrhoea (especially with blood), or severe dehydration
• Signs of serious liver problems (jaundice, dark urine)

Practical use tips (to get the best outcome)

• Take it consistently: Set alarms or use a dosing chart so you don’t miss doses.
• Stay hydrated: This can help if you have nausea or diarrhoea.
• Do not share antibiotics: Different infections need different treatments.
• Complete the course: Stopping early can increase relapse and resistance risk.
• Monitor symptom improvement: Some improvement is usually expected within a couple of days, depending on the infection. If symptoms worsen or do not improve, seek advice.
• Consider probiotics cautiously: Some people take probiotics to reduce antibiotic-associated diarrhoea. Speak to a pharmacist for guidance, particularly if you are immunocompromised or have severe illness.

Alternative options

The “best” antibiotic depends on the type of infection, the likely bacteria, and local resistance patterns. If clarithromycin is not suitable (due to allergies, interactions, or resistance), clinicians may consider other antibiotics, or sometimes non-antibiotic supportive care depending on diagnosis.

Possible alternatives (examples) may include:

• Amoxicillin or amoxicillin-clavulanate (for selected respiratory or sinus infections)
• Azithromycin (another macrolide; may be considered in some respiratory indications)
• Doxycycline (for certain respiratory or skin conditions, depending on local guidance and suitability)
• Cefalexin or other cephalosporins (for selected bacterial infections)
• Different regimens for H. pylori: Alternative combinations may be used if clarithromycin resistance is likely.

If clarithromycin causes intolerable side effects or is unsafe due to interactions, your pharmacist or doctor can discuss appropriate alternatives.

Market and legal context in Australia

In Australia, access to antibiotics is regulated to help ensure safe and effective use, and to reduce antimicrobial resistance. Depending on the specific product and formulation, clarithromycin is typically supplied in line with Australian regulatory requirements and prescription access rules.

Antibiotic stewardship is strongly encouraged in Australia. This means using antibiotics only when needed, using the correct dose for the correct duration, and choosing therapies that align with current local guidelines.

Antimicrobial resistance matters: Overuse or incorrect use of antibiotics can lead to bacteria becoming resistant, making future infections harder to treat.

Recent guidance and stewardship themes (general information)

Australian antibiotic guidance evolves as resistance patterns change. Key themes you may encounter in current recommendations include:

• Confirming bacterial causes where possible (and avoiding antibiotics for viral illnesses)
• Using local resistance data to guide antibiotic selection
• Reviewing H. pylori regimens based on likelihood of clarithromycin resistance and the best eradication strategy
• Limiting duration to the minimum effective based on the infection and clinical response
• Medication safety checks for interactions (including heart rhythm considerations and interactions with cholesterol medicines and anticoagulants)

Your pharmacist may ask screening questions about your medical history and current medicines to help ensure clarithromycin is appropriate and safe for you.

Delivery and availability (online pharmacy)

Clarithromycin products may be available through online pharmacies in Australia, depending on stock levels and the specific brand and strength. Delivery options vary by provider, location, and order cut-off times.

• Availability: Stock can change. If a product is temporarily unavailable, customer support may offer alternatives or restocking updates.
• Packaging: Items are typically dispatched in manufacturer packaging with clear labels and instructions.
• Delivery timeframe: Estimated delivery times depend on your address and shipping service.
• Privacy and handling: Online pharmacies generally provide discreet packaging and track-and-trace delivery.

If you are ordering for a child or require a specific formulation (e.g., suspension), check that the product matches what is intended before placing your order.

Storage and handling

• Store at room temperature unless your label states otherwise.
• Keep out of reach of children.
• Protect from moisture and heat.
• Liquid suspension: Some suspensions require refrigeration or specific preparation steps—follow the label closely.

FAQ – Clarithromycin

1) What infections does clarithromycin treat?

Clarithromycin treats selected bacterial infections, commonly involving the respiratory tract and some skin/soft tissue infections. It is also used in combination regimens for H. pylori eradication. It does not treat viral infections like colds or flu.

2) How fast should I feel better?

Many people notice improvement within 1–3 days. If you feel worse, develop severe symptoms, or do not improve after a few days, seek advice from a healthcare professional.

3) Can I take clarithromycin with food?

Many people tolerate clarithromycin better with or after food. However, recommendations can vary by product and formulation. Follow your label or pharmacist instructions for your specific medicine.

4) What should I do if I miss a dose?

Take it as soon as you remember. If it is close to the next dose, skip the missed dose. Do not take a double dose. If you’re unsure, ask your pharmacist.

5) Is it safe to drink alcohol while taking clarithromycin?

It’s best to avoid or minimise alcohol while taking clarithromycin because alcohol may worsen stomach side effects and adds strain on the liver. If you choose to drink, discuss your situation with a pharmacist, especially if you have liver issues or other medicines that interact.

6) Are there medicines I must avoid?

Clarithromycin can interact with several medicines (for example, certain statins, anticoagulants, some heart rhythm medicines, and medicines like colchicine in certain situations). Tell your pharmacist about all medicines and supplements you take.

7) Can clarithromycin cause diarrhoea?

Yes. Mild diarrhoea can occur. However, seek urgent advice if diarrhoea is severe, persistent, watery or bloody, or accompanied by fever or strong abdominal pain, as this can indicate a serious bowel condition.

8) Can I stop early if I feel better?

It’s important to finish the full course unless a clinician advises otherwise. Stopping early can increase relapse risk and antibiotic resistance.

9) What if I’m pregnant or breastfeeding?

Safety in pregnancy and breastfeeding depends on your circumstances and the infection being treated. Discuss options with a doctor or pharmacist. Do not start or change antibiotics without professional advice.

10) What are “antibiotic resistance” and why does it matter?

Resistance occurs when bacteria adapt so antibiotics no longer work as well. Using antibiotics only when appropriate, taking them correctly, and finishing the course helps slow resistance.

Important: This information is general and designed to help you use clarithromycin safely. Always read the product label and follow the advice of your healthcare professional for your specific situation.