If the risk is not zero why doesn’t everyone take PEP?

PEP involves taking a combination of medicines for 28 days. These medicines can have side effects some of which are common and others which can be serious.
Common side effects include feeling sick, diarrhoea, dizziness, headaches and difficulty sleeping.
Serious side effects include rash and changes in liver and kidney function.
Most patients tolerate the medication well.
The patient will need baseline blood and urine tests and follow up which may include further visits and tests.