Antibiotics
Penicillin’s (e.g., Amoxicillin, Penicillin V)
Absolute Contraindications
- Severe penicillin allergy (e.g., anaphylaxis)
Main Side Effects
- Rash (common in viral infections, e.g., EBV)
- Diarrhoea
- Hypersensitivity reactions (rare)
Main Interactions
- Methotrexate (reduced clearance, increasing toxicity risk)
Main Monitoring Requirements
- None typically required
Pregnancy & Breastfeeding
- Safe
Cephalosporin’s (e.g., Cefalexin)
Absolute Contraindications
- Severe hypersensitivity to cephalosporins or penicillin’s
Main Side Effects
- GI upset (diarrhoea)
- Hypersensitivity reactions
- Risk of Clostridium difficile infection
Main Interactions
- Warfarin (may enhance anticoagulant effect)
Main Monitoring Requirements
- None typically required
Pregnancy & Breastfeeding
- Safe
Macrolides (e.g., Erythromycin, Azithromycin, Clarithromycin)
Absolute Contraindications
- History of QT prolongation
- Severe hepatic impairment
Main Side Effects
- GI upset (nausea, diarrhoea)
- QT prolongation (risk of arrhythmia)
- Hepatotoxicity (rare)
Main Interactions
- Statins (increased risk of myopathy, especially with clarithromycin)
- Warfarin (enhanced anticoagulant effect)
Main Monitoring Requirements
- Liver function (if long-term use)
Pregnancy & Breastfeeding
- Generally safe in pregnancy and breastfeeding
Nitrofurantoin
Absolute Contraindications
- eGFR < 30 mL/min (risk of inefficacy and toxicity)
- Third trimester of pregnancy (risk of neonatal haemolysis) Main Side Effects
- GI upset
- Pulmonary reactions (acute or chronic)
- Peripheral neuropathy (rare)
Main Interactions
- Antacids (reduce absorption)
Main Monitoring Requirements
- Renal function if long-term use
Pregnancy & Breastfeeding
- Avoid in late pregnancy, generally safe for short-term use in breastfeeding
Tetracyclines (e.g., Trimethoprim & Doxycycline)
Absolute Contraindications
- Severe renal impairment (without dose adjustment)
- Pregnancy (first trimester due to folate antagonism)
Main Side Effects
- Hyperkalaemia
- GI upset
- Rash
Main Interactions
- Potassium-sparing diuretics (risk of hyperkalaemia)
- Methotrexate (additive folate antagonism)
Main Monitoring Requirements
- Renal function
- Potassium levels (if at risk)
Pregnancy & Breastfeeding
- Avoid in the first trimester, safe in breastfeeding
Fluoroquinolones (e.g., Ciprofloxacin, Levofloxacin, Ofloxacin)
Absolute Contraindications
- History of tendon disorders related to fluoroquinolones
- Children & adolescents (except in specific cases)
- Pregnancy and breastfeeding
- Myasthenia gravis (can worsen symptoms)
Main Side Effects
- GI upset (nausea, diarrhoea)
- Tendonitis or tendon rupture (e.g., Achilles tendon)
- CNS effects (e.g., dizziness, headache, seizures)
- QT interval prolongation (risk of arrhythmias)
- Rare: Peripheral neuropathy
Main Interactions
- Antacids, iron, and calcium supplements (reduce absorption; take at least 2 hours apart)
- NSAIDs (increased risk of seizures)
- Drugs causing QT prolongation (e.g., amiodarone, macrolides)
- Warfarin (enhanced anticoagulant effect)
Main Monitoring Requirements
- Renal function in elderly patients or those with impairment
- QT interval in patients at risk of arrhythmias
Pregnancy & Breastfeeding
- Contraindicated in both due to potential harm to fetal cartilage and joint development