Flucloxacillin EQL Pharma
Penicillinase-resistant penicillin antibiotic for staphylococcal infections
Quick Facts about Flucloxacillin EQL Pharma
Key Takeaways
- Targeted against staphylococci: Flucloxacillin is specifically designed to treat infections caused by penicillinase-producing Staphylococcus aureus that resist standard penicillins
- Take on an empty stomach: Food significantly reduces absorption; take 30-60 minutes before meals or 2 hours after eating for best effectiveness
- Complete the full course: Always finish the entire prescribed course of antibiotics, even if you feel better, to prevent antibiotic resistance
- Watch for liver warning signs: Cholestatic hepatitis is a rare but serious side effect, especially with courses over 14 days; report yellowing of skin or eyes immediately
- Not suitable for penicillin-allergic patients: Do not take flucloxacillin if you have ever had an allergic reaction to any penicillin antibiotic
What Is Flucloxacillin EQL Pharma and What Is It Used For?
Flucloxacillin EQL Pharma is a narrow-spectrum penicillin antibiotic that kills bacteria by disrupting their cell wall synthesis. It is specifically effective against penicillinase-producing staphylococci and is used to treat skin infections, bone infections, endocarditis, and other staphylococcal infections.
Flucloxacillin belongs to the isoxazolyl penicillin subgroup of beta-lactam antibiotics. Unlike standard penicillins such as amoxicillin or benzylpenicillin, flucloxacillin has been chemically modified to resist hydrolysis by beta-lactamase enzymes produced by certain bacteria, most notably Staphylococcus aureus. This resistance makes it the drug of choice for infections where penicillinase-producing staphylococci are the suspected or confirmed causative organisms.
The active substance, flucloxacillin, works by binding to penicillin-binding proteins (PBPs) in the bacterial cell wall. These proteins are essential for the final stage of cell wall synthesis, specifically the cross-linking of peptidoglycan chains. When flucloxacillin binds to PBPs, it prevents this cross-linking process, weakening the cell wall and ultimately leading to bacterial cell lysis and death. This mechanism of action is bactericidal, meaning it directly kills bacteria rather than simply halting their growth.
Flucloxacillin EQL Pharma is manufactured by EQL Pharma and is available as 1 g film-coated tablets. The film coating facilitates swallowing and protects the active ingredient during passage through the stomach. This formulation is intended for oral administration and is suitable for outpatient treatment of moderate to serious infections.
Common indications for flucloxacillin
Flucloxacillin is prescribed for a wide range of staphylococcal infections. The most common clinical indications include:
- Skin and soft tissue infections: Cellulitis, impetigo, wound infections, boils (furunculosis), carbuncles, abscesses, and infected eczema
- Bone and joint infections: Osteomyelitis (bone infection) and septic arthritis, where staphylococcal involvement is suspected
- Respiratory tract infections: Staphylococcal pneumonia, lung abscess, and empyema
- Endocarditis: Infection of the heart valves, often as part of combination therapy
- Surgical prophylaxis: Prevention of staphylococcal wound infections in certain surgical procedures
- Infected burns and traumatic wounds: Where staphylococcal colonisation or infection is confirmed or suspected
Methicillin-resistant Staphylococcus aureus (MRSA) is resistant to all beta-lactam antibiotics, including flucloxacillin. If MRSA infection is suspected or confirmed, alternative antibiotics such as vancomycin, linezolid, or daptomycin are required. Your doctor will select the appropriate antibiotic based on culture and sensitivity results.
How is flucloxacillin absorbed and metabolised?
When taken orally, flucloxacillin is absorbed from the gastrointestinal tract, although absorption is significantly reduced by food. Peak plasma concentrations are typically reached within 1 to 2 hours after administration. The drug is approximately 95% protein-bound in plasma, primarily to albumin. It is distributed to most body tissues and fluids, including bone tissue, which is important for treating osteomyelitis.
Flucloxacillin is partially metabolised in the liver, and both the unchanged drug and its metabolites are excreted primarily through the kidneys. The plasma elimination half-life is approximately 45 to 60 minutes in patients with normal renal function, which is why the drug is typically administered four times daily to maintain effective blood levels throughout the day.
What Should You Know Before Taking Flucloxacillin EQL Pharma?
Do not take flucloxacillin if you are allergic to penicillins. Use with caution if you have liver problems, kidney impairment, or a history of allergic reactions to cephalosporins. Inform your doctor about all other medications you are taking before starting treatment.
Before starting treatment with flucloxacillin, it is essential to inform your prescribing doctor or pharmacist about your complete medical history, current medications, and any known allergies. Several important factors may affect whether flucloxacillin is safe and appropriate for you.
Contraindications
You must not take Flucloxacillin EQL Pharma if:
- You are allergic to flucloxacillin, any other penicillin antibiotic (such as amoxicillin, ampicillin, or benzylpenicillin), or any of the other ingredients in the tablet
- You have a history of flucloxacillin-associated hepatic reactions (liver problems caused by previous use of flucloxacillin)
- You have a history of severe hypersensitivity (e.g., anaphylaxis) to other beta-lactam antibiotics such as cephalosporins or carbapenems
Allergic reactions to penicillin can range from mild skin rash to life-threatening anaphylaxis. If you have ever experienced swelling of the face, lips, or throat, difficulty breathing, or severe skin reactions after taking any penicillin antibiotic, do not take flucloxacillin. Tell your doctor immediately so an alternative antibiotic can be prescribed. Cross-reactivity with cephalosporins occurs in approximately 1-2% of penicillin-allergic patients.
Warnings and Precautions
Talk to your doctor before taking flucloxacillin if you:
- Have liver disease or impaired liver function: Flucloxacillin can cause cholestatic hepatitis, which may be severe. Risk factors include age over 55, female sex, and treatment courses exceeding 14 days
- Have kidney disease: Dose adjustments may be needed in patients with severe renal impairment (creatinine clearance below 10 mL/min)
- Are taking other medications: Several drug interactions exist that may affect the safety or efficacy of flucloxacillin
- Have a history of gastrointestinal disease: Particularly antibiotic-associated colitis (Clostridioides difficile infection)
- Are elderly: Older patients are at increased risk of hepatic side effects and may require closer monitoring
During treatment, your doctor may order blood tests to monitor liver function, particularly if the treatment course is expected to exceed two weeks. Signs of liver problems include yellowing of the skin or eyes (jaundice), dark urine, pale stools, persistent nausea, and abdominal pain. If you experience any of these symptoms, stop taking flucloxacillin and contact your doctor immediately.
Pregnancy and Breastfeeding
If you are pregnant, think you may be pregnant, or are planning to become pregnant, consult your doctor before taking flucloxacillin. Animal studies have not shown direct harmful effects on the developing foetus, and flucloxacillin has been used clinically during pregnancy when the benefits are considered to outweigh the risks. However, as with all medications during pregnancy, it should only be used when clearly necessary and under medical supervision.
Flucloxacillin is excreted in small amounts in breast milk. While this is generally considered safe for breastfed infants, there is a theoretical risk of sensitisation, diarrhoea, or candidiasis (thrush) in the nursing infant. Your doctor will weigh the benefits of breastfeeding and the benefits of treatment for you when making a recommendation. If your infant develops diarrhoea or a rash while you are taking flucloxacillin, inform your doctor.
How Does Flucloxacillin EQL Pharma Interact with Other Drugs?
Flucloxacillin interacts with methotrexate (increased toxicity), warfarin (altered anticoagulant effect), probenecid (increased flucloxacillin levels), and paracetamol (risk of metabolic acidosis). It may also reduce the effectiveness of oral contraceptives. Always inform your doctor about all medications you are taking.
Drug interactions can alter the way flucloxacillin works or increase the risk of side effects. It is crucial to inform your doctor and pharmacist about all medications you are currently taking, including prescription drugs, over-the-counter medications, herbal remedies, and dietary supplements. The following interactions are clinically significant and should be carefully considered.
Major Interactions
| Interacting Drug | Effect | Severity | Recommendation |
|---|---|---|---|
| Methotrexate | Reduced renal clearance of methotrexate, leading to increased plasma levels and potential toxicity | Major | Avoid combination or monitor methotrexate levels closely |
| Warfarin / Oral anticoagulants | Altered anticoagulant effect; penicillins may increase INR and bleeding risk | Major | Monitor INR frequently during co-administration and adjust warfarin dose as needed |
| Paracetamol (Acetaminophen) | Co-administration may increase risk of high anion gap metabolic acidosis (5-oxoprolinuria), especially in renally impaired patients | Major | Use with caution; monitor for signs of metabolic acidosis (rapid breathing, confusion, nausea) |
Minor Interactions
| Interacting Drug | Effect | Severity | Recommendation |
|---|---|---|---|
| Probenecid | Reduces renal tubular secretion of flucloxacillin, increasing its blood levels and prolonging its half-life | Moderate | Combination sometimes used intentionally; monitor for increased side effects |
| Oral contraceptives | Possible reduced efficacy of hormonal contraceptives due to altered gut flora affecting enterohepatic recirculation | Moderate | Use additional barrier contraception during treatment and for 7 days after completion |
| Mycophenolate mofetil | Reduced bioavailability of mycophenolate; possible reduced immunosuppressive effect | Moderate | Monitor mycophenolate levels and clinical response closely during and shortly after treatment |
| Typhoid vaccine (oral) | Antibiotics may inactivate oral typhoid vaccine if given concurrently | Minor | Complete antibiotic course at least 3 days before giving oral typhoid vaccine |
Food significantly reduces the absorption of flucloxacillin. Take the tablets on an empty stomach, ideally 30 to 60 minutes before a meal or at least 2 hours after eating. Swallow the tablet whole with a full glass of water. Do not crush or chew the film-coated tablet.
What Is the Correct Dosage of Flucloxacillin EQL Pharma?
The usual adult dose is 250 mg to 1 g taken four times daily (every 6 hours), depending on the severity of the infection. The tablets should be taken on an empty stomach. Treatment duration is typically 5 to 7 days for mild infections, but may extend to several weeks for severe or deep-seated infections.
The dosage of flucloxacillin depends on the type and severity of the infection, the patient's age, weight, and kidney function. Your doctor will determine the appropriate dose for your specific condition. Always follow the prescribed dosage and do not change it without consulting your doctor.
Adults
Standard adult dosing
- Mild to moderate infections: 250-500 mg every 6 hours (four times daily)
- Severe infections: 1 g every 6 hours (four times daily)
- Osteomyelitis: 1-2 g every 6 hours, often initiated intravenously then stepped down to oral therapy
- Endocarditis: High-dose intravenous therapy initially; oral step-down with 1-2 g every 6 hours under specialist guidance
For skin and soft tissue infections such as cellulitis or impetigo, a typical course of 500 mg to 1 g four times daily for 5 to 7 days is standard. In more complex infections, your doctor may prescribe longer courses. The maximum recommended daily dose for adults is 8 g (in divided doses), though such high doses are typically reserved for severe systemic infections and are often given intravenously.
Children
Paediatric dosing (oral)
- Under 2 years: One quarter of the adult dose
- 2-10 years: Half the adult dose
- Over 10 years: Adult dose
Note: Flucloxacillin EQL Pharma 1 g tablets are not suitable for young children who cannot swallow large tablets. Oral liquid formulations are available from other manufacturers for paediatric use.
Children's doses are typically calculated based on body weight, with a general guideline of 12.5 to 25 mg/kg/day divided into four doses for mild infections, increasing to 50 mg/kg/day or more for severe infections. Your child's doctor will determine the precise dose based on the specific infection and the child's weight. It is important that flucloxacillin is also given to children on an empty stomach for optimal absorption.
Elderly
Elderly patients do not routinely require dose adjustments for flucloxacillin, but closer monitoring is recommended. Older adults are at increased risk of hepatic adverse effects, particularly cholestatic jaundice and hepatitis. The risk is further increased in patients over 55 years of age, females, and those receiving prolonged courses exceeding 14 days. Renal function should be assessed before and during treatment, as age-related decline in kidney function may affect drug clearance.
Missed Dose
If you forget to take a dose, take it as soon as you remember. However, if it is nearly time for your next dose (within 2 hours), skip the missed dose and continue with your regular schedule. Do not take a double dose to make up for the one you missed. Try to space your doses evenly throughout the day to maintain consistent blood levels of the antibiotic.
Overdose
If you accidentally take more flucloxacillin than prescribed, contact your doctor, pharmacist, or local poison control centre immediately. Symptoms of overdose may include nausea, vomiting, diarrhoea, and abdominal pain. In very large overdoses, neurological symptoms such as seizures can theoretically occur, although this is rare with oral formulations. Treatment is generally supportive, and flucloxacillin can be removed from the blood by haemodialysis if necessary.
What Are the Side Effects of Flucloxacillin EQL Pharma?
Common side effects include gastrointestinal symptoms (nausea, diarrhoea, abdominal discomfort) and skin rash. Uncommon but serious side effects include cholestatic hepatitis (liver inflammation with jaundice), severe allergic reactions, and Clostridioides difficile-associated diarrhoea. Seek immediate medical attention for signs of liver problems or severe allergic reactions.
Like all medicines, flucloxacillin can cause side effects, although not everybody gets them. Most side effects are mild and resolve after treatment is completed. However, some side effects can be serious and require immediate medical attention. The following list categorises side effects by their frequency of occurrence based on clinical data and post-marketing surveillance.
Very Common (affects more than 1 in 10 people)
- Gastrointestinal disturbances: nausea, diarrhoea, abdominal discomfort, flatulence
Common (affects 1 to 10 in 100 people)
- Skin rash (maculopapular or urticarial)
- Vomiting
- Indigestion (dyspepsia)
- Oral or vaginal candidiasis (thrush) due to disruption of normal flora
Uncommon (affects 1 to 10 in 1,000 people)
- Cholestatic hepatitis (liver inflammation with jaundice) — may occur up to 2 months after treatment ends
- Pruritus (itching) without rash
- Fever
- Joint pain (arthralgia)
- Muscle pain (myalgia)
Rare (affects fewer than 1 in 1,000 people)
- Anaphylaxis (severe allergic reaction with breathing difficulty and cardiovascular collapse)
- Angioedema (swelling of face, lips, tongue, or throat)
- Stevens-Johnson syndrome and toxic epidermal necrolysis (severe skin reactions)
- Interstitial nephritis (kidney inflammation)
- Clostridioides difficile-associated diarrhoea (pseudomembranous colitis)
- Blood disorders: neutropenia, thrombocytopenia, haemolytic anaemia
- Serum sickness-like reactions
- High anion gap metabolic acidosis (5-oxoprolinuria), especially with concurrent paracetamol use
Stop taking flucloxacillin and seek urgent medical help if you experience:
- Signs of a severe allergic reaction: Swelling of the face, lips, tongue, or throat; difficulty breathing or swallowing; severe dizziness; widespread rash with itching
- Signs of liver problems: Yellowing of the skin or whites of the eyes (jaundice); dark urine; pale stools; severe nausea or vomiting; abdominal pain; unusual tiredness
- Severe or bloody diarrhoea: This may indicate Clostridioides difficile infection, which requires prompt treatment
- Severe skin reactions: Widespread rash with blisters or peeling, mouth sores, fever
The risk of cholestatic hepatitis is a particular concern with flucloxacillin. Research published in peer-reviewed journals has identified several risk factors that increase the likelihood of this adverse effect. Patients over 55 years of age, females, and those receiving treatment courses longer than 14 days are at the highest risk. Hepatic reactions may develop during treatment or up to two months after the course is completed. The majority of cases resolve spontaneously after the drug is discontinued, although rare cases of liver failure have been reported.
A strong genetic association has been identified: individuals carrying the HLA-B*5701 allele have a significantly increased risk of flucloxacillin-induced liver injury. However, routine genetic testing before prescribing flucloxacillin is not yet standard practice in most healthcare systems.
How Should You Store Flucloxacillin EQL Pharma?
Store flucloxacillin tablets below 25°C in the original packaging to protect from moisture. Keep out of reach and sight of children. Do not use after the expiry date printed on the packaging.
Proper storage of medications is essential to ensure they remain effective and safe throughout their shelf life. Flucloxacillin EQL Pharma 1 g film-coated tablets should be stored according to the following guidelines:
- Temperature: Store below 25°C (77°F) at room temperature. Do not refrigerate or freeze
- Packaging: Keep the tablets in the original blister packaging to protect from moisture and light
- Child safety: Store in a place that is out of the reach and sight of children. Consider using a locked medicine cabinet
- Expiry date: Do not use the tablets after the expiry date stated on the blister and carton. The expiry date refers to the last day of that month
- Disposal: Do not dispose of unused medicines via household waste or wastewater. Return any unused or expired tablets to your local pharmacy for proper disposal to help protect the environment
If the tablets appear discoloured, crumbled, or have an unusual smell, do not take them even if they are within the expiry date. Contact your pharmacist for advice and a replacement prescription.
What Does Flucloxacillin EQL Pharma Contain?
Each film-coated tablet contains 1 g of flucloxacillin (as flucloxacillin sodium). The tablet also contains inactive ingredients (excipients) that give it its structure, coating, and stability.
Understanding the composition of your medication is important, particularly if you have known allergies or intolerances to specific excipients. The complete composition of Flucloxacillin EQL Pharma 1 g film-coated tablets is as follows:
Active ingredient
Each tablet contains flucloxacillin sodium, equivalent to 1 g of flucloxacillin. Flucloxacillin sodium is the sodium salt form of flucloxacillin, which provides improved solubility and stability compared to the free acid form. Note that the sodium content may be relevant for patients on sodium-restricted diets.
Excipients (inactive ingredients)
The tablet core and film-coating contain various excipients that serve specific pharmaceutical functions:
- Microcrystalline cellulose: A bulking agent that gives the tablet its structure
- Croscarmellose sodium: A disintegrant that helps the tablet break apart in the stomach for proper absorption
- Magnesium stearate: A lubricant used during manufacturing to prevent the tablet from sticking to machinery
- Hypromellose: Used in the film coating to protect the tablet and aid swallowing
- Titanium dioxide (E171): A white colouring agent used in the film coating
- Macrogol: A plasticiser used in the film coating
If you know you are allergic or intolerant to any of these excipients, inform your doctor or pharmacist before taking this medication. Patients with rare hereditary problems of galactose intolerance, total lactase deficiency, or glucose-galactose malabsorption should consult their doctor, although this formulation does not typically contain lactose as an excipient.
Frequently Asked Questions about Flucloxacillin EQL Pharma
Medical References
All medical information in this article is based on peer-reviewed research and international clinical guidelines. Evidence level: 1A.
- European Medicines Agency (EMA). Summary of Product Characteristics: Flucloxacillin. EMA, 2024. Available at: www.ema.europa.eu
- Joint Formulary Committee. British National Formulary (BNF) 86. BMJ Group and Pharmaceutical Press, 2024. Flucloxacillin monograph.
- World Health Organization. WHO Model List of Essential Medicines – 23rd List. WHO, 2023.
- Daly AK, Donaldson PT, Bhatnagar P, et al. HLA-B*5701 genotype is a major determinant of drug-induced liver injury due to flucloxacillin. Nature Genetics. 2009;41(7):816-819. doi:10.1038/ng.379
- Andrews T, Thompson M, Buckley DI, et al. Interventions to influence consulting and antibiotic use for acute respiratory tract infections in children: a systematic review and meta-analysis. PLoS ONE. 2012;7(1):e30334.
- Steer AC, Danchin MH, Carapetis JR. Group A streptococcal infections in children. Journal of Paediatrics and Child Health. 2007;43(4):203-213.
- European Committee on Antimicrobial Susceptibility Testing (EUCAST). Breakpoint tables for interpretation of MICs and zone diameters, Version 14.0. 2024.
- National Institute for Health and Care Excellence (NICE). Antimicrobial prescribing guidelines. NICE, 2024.
- Lim WS, Baudouin SV, George RC, et al. BTS guidelines for the management of community acquired pneumonia in adults. Thorax. 2009;64(Suppl 3):iii1-55.
- Tong SYC, Davis JS, Eichenberger E, Holland TL, Fowler VG Jr. Staphylococcus aureus infections: epidemiology, pathophysiology, clinical manifestations, and management. Clinical Microbiology Reviews. 2015;28(3):603-661.
About Our Medical Editorial Team
This article has been written and reviewed by the iMedic Medical Editorial Team, which includes licensed physicians with specialisation in pharmacology, infectious disease, and clinical microbiology.
Peer Review Process
All medical content is reviewed by at least two licensed specialist physicians before publication.
Fact-Checking
All medical claims are verified against peer-reviewed sources and international guidelines.
Update Frequency
Content is reviewed and updated at least every 12 months or when new research emerges.
Corrections Policy
Any errors are corrected immediately with transparent changelog. Read more
Medical Editorial Board: iMedic has an independent medical editorial board consisting of specialist physicians in pharmacology, infectious disease, and clinical microbiology.