For PEP to have the best chance of working it must be taken exactly as instructed by a doctor and for 28 days. Skipping doses or not taking the pills for the full month makes it likely that PEP will not work.
If a dose is missed take the next dose as soon as you remember – don’t take double the dose.
It is common for people taking PEP to get side effects. These will stop once the course of drugs has been completed but for some people they can make sticking with PEP difficult. Headaches, tiredness, feeling sick and diarrhoea are common side effects.
If you are finding the treatment difficult, speak to the clinic that gave it to you; they can give you medication to help with side effects. Because of side effects some people need to take time off work or study while they are on PEP. Also, as recreational drugs can have dangerous interactions with HIV medication, it’s advisable to not use them while taking PEP.
To be sure that no infection has taken place, three months after the course of PEP drugs has been completed an HIV test is carried out. If you decide not to take PEP, an HIV test is recommended anyway, along with a check up for sexually transmitted infections.
When someone is taking PEP they will be advised not to have any further unprotected sex during the 28 days of treatment as this will make it more likely that PEP does not work.