Background There is no published evidence on the need for routine blood monitoring for people requiring daily oral acyclovir. Locally clinical practice differred between services. Dose reduction in moderate to severe renal impairment is recommended. Guidance for intravenous administration recommends measuring full blood count (FBC), renal (U&E) and liver function (LFTs) periodically.

Methods In 2013 we reviewed clinical notes coded for herpes suppression to establish whether BASHH and local standards were met for management of herpes suppression and routine blood monitoring.

Results 41 cases were reviewed. 32 (73%) had baseline blood tests. Of these 6/32 (19%) had abnormal results: 2 raised LFTS, 2 low estimated Glomerular Filtration Rate (eGFR), 2 low neutrophils – all resolved on repeating except one with fluctuating neutropenia. 19/32 (47%) had bloods repeated at our service and additional 16% advised to attend GP. Only 1/19 (5%) had normal baseline bloods, low eGFR at one month, but normal at 2 months.

Discussion 19% of those tested had blood abnormalities at baseline, but only 3% had on-going abnormalities likely affected by acyclovir. We recommend checking U&E, LFT and FBC at baseline. If normal no further monitoring is needed. If mildy abnormal repeat but continue aciclovir. If significantly low eGFR, leucopenia or elevated LFTs either dose reduce or stop acyclovir and investigate.