HIV post exposure prophylaxis

If the source is known to be HIV positive or assessed as high risk, PEP should be considered. The decision to start treatment must incorporate the injured healthcare worker’s perception of risk. Nationally, the risk of transmission is no more than 0.3%. Local departmental guidelines may include guidance on local risk based on the local incidence of HIV. 

If the source patient is known to be HIV positive and their viral load is known this can further inform the decision. The Chief Medical Officer’s Expert Advisory Group on AIDS advise that if the source’s viral load is undetectable (<200 copies HIV RNA/ml), PEP is not recommended. Although there may still be a theoretical risk of transmission, it is extremely low. PEP should still, however, be offered to those who are anxious about the risk (9).

If the assessing clinician or patient require further guidance on assessing or discussing risk, seeking advice from the infectious diseases or microbiology team may beappropriate.

If HIV PEP is to be prescribed, it should be started as soon as possible after exposure, ideally within 1 hour. It is not recommended beyond 72 hours post exposure (7).

Emergency departments should have packs containing a 3-5 day supply of PEP (remember to account for weekends and bank holidays) available to dispense immediately. Packs should contain, in line with DoH guidance (109):

  • Truvada (245mg tenofovir and 200mg emtricitabine) once daily.
  • Raltegravir 400mg twice per day.

Remember that this presentation is likely to be out of hours, and a source of some concern for the healthcare worker. Provide some written information for reference at home about PEP, such as the information leaflet produced by the HIV Pharmacy Association (110).

Don’t forget to consider:

  • HIV PEP should not be taken with rifampicin.
  • It should be taken at least 4 hours after taking any vitamin supplements, or calcium, iron, and magnesium supplements. 
  • Patients using oral contraception should be advised to use barrier contraception while taking PEP and awaiting results.

If pregnancy cannot be excluded then a pre-treatment pregnancy test should be performed, but pregnancy should not preclude the use of PEP. There is no evidence to suggest decreased efficacy or toxicity, and HIV PEP is commonly used during pregnancy.


Department of Health. HIV post-exposure prophylaxis: guidance from the UK Chief Medical Officers’ Expert Advisory Group on AIDS. 2008. [accessed May 2020].

British Medical Association. Needlestick injuries and blood-borne viruses: testing adults who lack capacity. 2020. [accessed May 2020].

Expert Advisory Group on AIDS. Updated recommendations for HIV post-exposure prophylaxis following occupational exposure to a source with undetectable HIV viral load. 2013. [accessed June 2020].

Expert Advisory Group on AIDS. Change to recommended regimen for post -exposure prophylaxis. 2014. [accessed May 2020].

HIV Pharmacy Association. Expert Advisory Group on AIDS PEP information pack. 2018. [accessed May 2020].