Flucloxacillin 500 mg: Uses, Dosage, and Side Effects

Bacterial infections can range from mild skin issues to more severe conditions, such as bone or joint infections. One of the most trusted antibiotics doctors use against Staphylococcus bacteria is Flucloxacillin 500 mg. It’s been prescribed for decades and remains highly effective for specific infections.

If your doctor has recommended flucloxacillin, you might be wondering: Why this medicine? How do I take it? What should I expect? In this article, we’ll break everything down in simple terms—from what the drug does to how to take it safely.

What Is Flucloxacillin?

Flucloxacillin is part of the penicillin family of antibiotics. Unlike standard penicillin, it’s resistant to certain enzymes that bacteria use to protect themselves. This makes flucloxacillin especially useful for infections caused by penicillin-resistant Staphylococcus.

Key facts about flucloxacillin:

• Form: Capsules, liquid suspension, or injections

• Strength: 500 mg is the standard adult dose

• How it works: It prevents bacteria from building strong cell walls. Without these walls, bacteria can’t survive, and the infection clears.

Conditions Treated with Flucloxacillin

Doctors typically prescribe flucloxacillin when they suspect an infection caused by Staphylococcus bacteria. Common conditions include:

• Skin infections: cellulitis, impetigo, boils, abscesses

• Wound infections: cuts, burns, or surgical wounds that become infected

• Bone infections (osteomyelitis): a serious infection requiring longer treatment

• Joint infections (septic arthritis): bacteria damaging the joint

• Respiratory infections, such as staphylococcal pneumonia (less common)

• Endocarditis: a rare but life-threatening infection of the heart lining

Recommended Dosage and How to Take It

• Adults: 500 mg four times a day (every 6 hours)

• Children: Smaller doses, adjusted for body weight

• Severe infections: Higher doses may be prescribed under close medical supervision

Tips for taking flucloxacillin:

Take it on an empty stomach (1 hour before or 2 hours after meals).
Swallow with a full glass of water—don’t chew capsules.
Spread doses evenly across the day.
Always finish the course, even if you feel better sooner.

Possible Side Effects

Most people tolerate flucloxacillin well, but some side effects can occur.

Mild and common effects:

• Upset stomach or nausea

• Diarrhea

• Mild rash

Serious but rare effects (seek medical help immediately):

• Liver problems: yellowing of skin/eyes, dark urine, or extreme tiredness

• Allergic reactions: swelling of the face or throat, difficulty breathing, widespread rash

• Severe diarrhea linked to Clostridium difficile infection

Safety Considerations

Not everyone can safely take flucloxacillin. Tell your doctor if you:

• Are allergic to penicillin or similar antibiotics

• Have liver or kidney problems

• Have ever developed jaundice after taking flucloxacillin

• Are you pregnant or breastfeeding? (it can be safe, but only under medical guidance.)

Why You Should Complete the Full Course

One of the most common mistakes people make with antibiotics is stopping too soon, once they feel better. Doing this can leave some bacteria alive, allowing them to grow back stronger and become resistant to antibiotics in the future.

Finishing your prescribed course ensures the infection is fully cleared and helps protect against antibiotic resistance.

Practical Advice for Patients

Here are some simple tips to make your treatment easier:

• Set phone reminders so you don’t forget your dose

• Drink plenty of water during the course

• Avoid alcohol, as both alcohol and flucloxacillin are processed by the liver

• Never share your antibiotics with anyone else

• Store your capsules in a cool, dry place away from sunlight

Frequently Asked Questions

How fast does flucloxacillin work?

The vast majority of patients will experience improvement within 2–3 days. Still, of course, you’ll need to take the full regimen.

Can I take it with food?

It is most effective on an empty stomach. You may take it with a small meal if it upsets your stomach, but absorption may be decreased.

Can I drink alcohol on it?

Alcohol won’t affect flucloxacillin, but it may make you more likely to have side effects on your liver. Limiting alcohol is best.

What if I miss a dose?

Take your next dose as soon as you remember, unless it is almost time for your next dose. If so, skip the missed dose—don’t take a double.

Is it safe in pregnancy?

Yes, in most cases; however, only if recommended by your doctor.

Can I take it if I’m allergic to penicillin?

No. If you’ve ever taken penicillin and had an allergic reaction, you should never be given flucloxacillin.

Can it damage the liver?

Liver disease is unusual, but if you see jaundice (yellowing of eyes or skin), seek medical attention.

Final Thoughts

Flucloxacillin 500mg is an antibiotic with proven efficacy for years, especially when it comes to Staphylococcus germs. Whether it’s for a skin infection, a bone infection, or any sort of wound complication, it can be very effective if taken correctly.

for the best results:

• Take it exactly as prescribed

• Complete the full course

• Watch for possible side effects

• Ask your doctor if you have any questions

And by taking these measures, you give yourself the greatest chance of a full recovery and help slow a growing problem: that of antibiotic resistance.