{"ok":true,"entry":{"slug":"aciclovir","kind":"medication","name":"aciclovir","aliases":["acyclovir","Zovirax"],"brands_sg":["Zovirax","Virox","Herperax","Avorax","Virless"],"class":"antiviral","tags":["other"],"use_for":"nhs: cold sores, shingles, chickenpox, genital herpes","use_after":"nhs: started as early as possible after it is prescribed","use_duration":null,"take_with":"nhs: plenty of water, especially with kidney problems","pros":["nhs: most adults can use it; children usually the cream","nhs: comes as tablets, cream and eye ointment","nhs: nothing known to affect the cream or eye ointment"],"cons":["nhs: headache, dizziness, nausea, diarrhoea, rash","nhs: rare liver, kidney and blood-cell problems","sg register: all 34 sg rows are prescription only"],"dose_note":"no singapore package insert was read and healthhub has no aciclovir leaflet. the us label for acyclovir tablets states \"Acute Treatment of Herpes Zoster: 800 mg every 4 hours orally, 5 times daily for 7 to 10 days\" — 800 mg five times a day is the highest oral regimen on that label; the genital-herpes regimens on the same label are lower (200 mg five times daily, or 400 mg twice daily for suppression). nhs does not quote a maximum and says how much to use depends on which type it is. in singapore the prescriber sets the dose.","dosage":null,"ul_status":null,"sg_class":"prescription-only","cautions":["past reaction to aciclovir or valaciclovir (nhs)","kidney problems — nhs stresses drinking water","weakened immune system — nhs: advice before cold-sore cream","pregnancy or breastfeeding — nhs asks to check first"],"clashes":[{"src":["nhs_acv_mix"],"note":"nhs lists it among medicines that may not mix well with some aciclovir tablets","with":"probenecid"},{"src":["nhs_acv_mix"],"note":"nhs lists it among medicines that may not mix well with some aciclovir tablets","with":"cimetidine"},{"src":["nhs_acv_mix"],"note":"nhs lists it among medicines that may not mix well with some aciclovir tablets","with":"mycophenolate mofetil"}],"sources":[{"id":"hsa_register","url":"https://data.gov.sg/datasets/d_767279312753558cbf19d48344577084/view","label":"HSA — Listing of Registered Therapeutic Products (data.gov.sg dataset d_767279312753558cbf19d48344577084), Forensicclassification column; all 5,511 rows cached at /tmp/hsa_all.json and filtered locally (not re-fetched), 34 aciclovir/acyclovir rows (valaciclovir excluded), 27 Aug 2026","quote":"ZOVIRAX CREAM 5% w/w SIN01191P · VIROX TABLET 400 mg SIN11658P · HERPERAX SIN09393P · AVORAX SIN09254P · VIRLESS SIN08532P — ATC J05AB01 and D06BB03; all 34 rows read Forensicclassification \"Prescription Only\"","accessed":"2026-08-27"},{"id":"nhs_acv_about","url":"https://www.nhs.uk/medicines/aciclovir/","label":"NHS medicines A–Z — Aciclovir (Zovirax): what aciclovir is for (reviewed 23 February 2026)","quote":"Aciclovir is an antiviral medicine used to treat certain infections … cold sores; shingles; chickenpox; genital herpes; herpes simplex eye infections","accessed":"2026-08-27"},{"id":"nhs_acv_howto","url":"https://www.nhs.uk/medicines/aciclovir/","label":"NHS medicines A–Z — Aciclovir: how to use aciclovir","quote":"start taking the tablets as soon as possible after you've been prescribed them … drink plenty of water while taking aciclovir tablets – this is particularly important if you have kidney problems","accessed":"2026-08-27"},{"id":"nhs_acv_side","url":"https://www.nhs.uk/medicines/aciclovir/","label":"NHS medicines A–Z — Aciclovir: side effects","quote":"Common side effects of aciclovir tablets include: headache; feeling dizzy or faint; feeling sick (nausea) or being sick (vomiting); diarrhoea; stomach ache; a rash … problems with your liver … problems with your kidneys … changes with your blood cells","accessed":"2026-08-27"},{"id":"nhs_acv_who","url":"https://www.nhs.uk/medicines/aciclovir/","label":"NHS medicines A–Z — Aciclovir: who can and cannot use aciclovir","quote":"Most adults can use aciclovir. Children can usually use the cream or ointment … you may not be able to use it if you've had an allergic reaction to aciclovir or a similar medicine called valaciclovir in the past.","accessed":"2026-08-27"},{"id":"nhs_acv_mix","url":"https://www.nhs.uk/medicines/aciclovir/","label":"NHS medicines A–Z — Aciclovir: using aciclovir with other medicines, food and drink","quote":"No medicines are known to affect aciclovir cream or eye ointment … These include: probenecid (a medicine used to treat gout); cimetidine … mycophenolate mofetil","accessed":"2026-08-27"},{"id":"fda_acv_dose","url":"https://api.fda.gov/drug/label.json?search=openfda.generic_name:%22acyclovir%22&limit=5","label":"US label for acyclovir tablets (effective 2026-02-04) via openFDA drug/label.json, Dosage and Administration","quote":"Acute Treatment of Herpes Zoster: 800 mg every 4 hours orally, 5 times daily for 7 to 10 days. Genital Herpes: Treatment of Initial Genital Herpes: 200 mg every 4 hours, 5 times daily for 10 days.","accessed":"2026-08-27"}],"brand_certs":null,"updated_at":"2026-08-29T16:16:10.48466+08:00"},"disclaimer":"kozen-x is not a medical device and does not give medical advice. it lists what published sources have written down. absence of a record is not the same as safe."}