Pivmecillinam – Specialist antibiotic with unique activity against UTI bacteria.
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What is Pivmecillinam?
Pivmecillinam (Selexid) is a specialized antibiotic with unique effectiveness against gram-negative bacteria that commonly cause urinary tract infections. Its specific activity profile makes it particularly valuable for uncomplicated UTIs and situations where first-line antibiotics may not be suitable.
Book an online consultation if you’re experiencing UTI symptoms such as burning urination, frequent urination, or pelvic discomfort, especially if you’ve had recurrent infections or previous antibiotic treatments. Our GPs can assess your symptoms and determine if Pivmecillinam or other UTI treatments are appropriate for your specific condition.
What is Pivmecillinam used for?
- Uncomplicated urinary tract infections (UTIs)
- Cystitis (bladder infections)
- Recurrent urinary tract infections
- UTIs caused by E. coli
- UTIs resistant to first-line antibiotics
- Lower urinary tract infections in women
- Acute uncomplicated cystitis
How does Pivmecillinam work?
A unique β-lactam antibiotic that specifically targets gram-negative bacteria common in UTIs by inhibiting cell wall synthesis through a mechanism different from other penicillins.
Dosage and Administration
Adults
400mg three times daily for 3-7 days. Take with food to improve absorption and reduce stomach upset.
Children
20-40mg per kg daily in divided doses—specialist supervision usually required.
Important Notes
- Take with food to reduce nausea and improve absorption.
- Complete the full course even if symptoms improve quickly.
- Take at evenly spaced intervals (every 8 hours).
- Drink plenty of fluids during treatment.
Side Effects
Common Side Effects
- Nausea and vomiting
- Diarrhoea
- Abdominal pain
- Headache
- Dizziness
- Skin rash
Serious Side Effects
Seek immediate medical attention if you experience:
- Severe allergic reactions
- Severe diarrhoea (C. difficile infection)
- Liver problems
- Blood disorders (rare)
- Stevens-Johnson syndrome (very rare)
Important Warnings
- Tell your GP if you're allergic to penicillins or other β-lactam antibiotics.
- May cause cross-reactivity in people with penicillin allergies.
- Take with food to reduce stomach upset and improve absorption.
- Tell your GP if you have kidney or liver problems.
- Stop and contact GP if severe diarrhoea or skin rash develops.
Drug Interactions
Tell your GP if you're taking any of the following medications:
- Probenecid—may increase pivmecillinam levels.
- Live vaccines—may reduce vaccine effectiveness during treatment.
- Methotrexate—may increase methotrexate toxicity.
- Generally fewer interactions than many other antibiotics.
Frequently Asked Questions
Why is Pivmecillinam specifically good for UTIs?
Pivmecillinam has unique activity against E. coli and other gram-negative bacteria that commonly cause UTIs, and it concentrates well in urine, making it highly effective for bladder infections.
How is Pivmecillinam different from Amoxicillin?
Pivmecillinam has much better activity against gram-negative bacteria like E. coli that cause most UTIs, while Amoxicillin is more effective against gram-positive bacteria.
Can I take Pivmecillinam if I'm allergic to penicillin?
There's a risk of cross-reactivity, so tell your GP about any penicillin allergies. They may choose an alternative antibiotic or prescribe with caution.
Why do I need to take it with food?
Taking Pivmecillinam with food significantly improves absorption and reduces the nausea that can occur with this antibiotic.
Medically Reviewed by: Mohammed Hassan - Independent Prescriber
Last Updated: 2025-01-14