Cytapen

Indications

Phenoxymethylpenicillin (penicillin V) is an antibiotic used for mild to moderate infections such as strep throat and tonsillitis, scarlet fever, some ear and skin infections, and dental infections. It is also used long term to prevent rheumatic fever from coming back, and to prevent pneumococcal infection in people without a working spleen.

How It Works

It stops bacteria from building their cell walls, so they burst and die.

Dosage and Administration

Adults and children over 12: usually 500 mg every 6 hours, increased to up to 1 g every 6 hours in severe infection, as prescribed. Strep throat is usually treated for 10 days. Prevention of rheumatic fever: commonly 250 mg twice a day, continued for as long as the doctor advises. Children under 12: as prescribed by age or weight. Take on an empty stomach, at least 30 minutes before food or 2 hours after, at evenly spaced times, and finish the full course.

Interactions

• It can increase the levels and side effects of Methotrexate.
• Probenecid raises penicillin levels.
• It may change the effect of Warfarin.
• Tetracycline antibiotics may reduce its effect.
• It can make the oral typhoid vaccine less effective.

Contraindications

Allergy to penicillin or any penicillin-type antibiotic.

Side Effects

Common: nausea, diarrhoea, stomach upset and thrush (yeast infection) of the mouth or vagina. A mild itchy rash can also occur.

Get urgent medical help for signs of a serious allergic reaction (swelling of the face, lips or throat, difficulty breathing, widespread hives or rash), a blistering or peeling skin rash, or severe, watery or bloody diarrhoea, which can happen during or weeks after treatment.

Pregnancy and Lactation

Penicillins are widely used in pregnancy and are not known to harm the baby. Small amounts pass into breast milk; it is generally safe while breastfeeding, but watch the baby for diarrhoea, thrush or rash.

Precautions and Warnings

• Tell the doctor about any previous reaction to penicillin or other antibiotics, and about kidney disease.
• It does not work against viral infections such as colds or flu.
• Do not stop early, even if you feel better, as the infection may come back.

Overdose

Overdose mainly causes nausea, vomiting and diarrhoea. Very high levels in people with kidney failure can cause seizures. Seek medical advice.

Therapeutic Class

Penicillin antibiotic.

Storage

Store tablets below 30°C in a dry place, away from light and out of the reach of children. After mixing, keep the oral solution or suspension in a fridge at 2 to 8°C and use it within the time stated on the pack.