Antivirals

[Bell’s palsy] Adjunct only. "Sometimes antiviral medications may also be prescribed to help increase the chance of recovering facial function," always with a steroid; StatPearls: most cases improve "with early corticosteroid therapy, with antivirals considered in select cases." Ramsay Hunt syndrome needs a higher antiviral dose and longer steroid course.

[PAX] Nirmatrelvir/ritonavir — for mild-to-moderate COVID-19 in adults at high risk; "Initiate PAXLOVID treatment as soon as possible after diagnosis of COVID-19 and within 5 days of symptom onset." IDSA (10/14/2025) "recommends nirmatrelvir/ritonavir over no antiviral treatment" for high-risk patients, and IDSA's approach section (guideline page published Sept 23, 2026) says it "should be the first option considered for ambulatory patients with mild to moderate COVID-19." Boxed CYP3A drug-interaction warning; "not approved for use as pre-exposure or post-exposure prophylaxis"; common effects "dysgeusia and diarrhea." [RDV] Remdesivir (IV) — outpatient 3-day course within 7 days of symptoms as the second choice (CDC); hospitalized 5 days, or 10 days if on invasive ventilation or ECMO (label); hepatic labs and PT before; observe 1 hour after infusion; not with chloroquine or hydroxychloroquine. Molnupiravir — only when the others are not accessible or appropriate; "low efficacy against severe outcomes." No doses here.

IV acyclovir — empiric for every suspected encephalitis. "Patients presenting with clinical features consistent with acute encephalitis should receive empiric intravenous acyclovir while awaiting HSV polymerase chain reaction (PCR) results." The label indication is "the treatment of herpes simplex encephalitis." Safety: "intended for intravenous infusion only, and should not be administered topically, intramuscularly, orally, subcutaneously, or in the eye"; "Intravenous infusions must be given over a period of at least 1 hour to reduce the risk of renal tubular damage"; "must be accompanied by adequate hydration"; concentration "approximately 7 mg/mL or lower." Watch creatinine, neurotoxicity (lethargy, tremors, confusion, hallucinations) and infusion-site phlebitis ("approximately 9%" — the drug is alkaline). Dose uses ideal body weight in obesity. No antiviral treats West Nile — acyclovir is continued only if HSV is not excluded.

[Shingles] First-line — start early. CDC: "There are three preferred antiviral drugs available for the initial treatment of shingles": acyclovir, valacyclovir and famciclovir; they "accelerate the resolution of lesions; reduce the development of new lesions and viral shedding; and decrease the severity of acute pain." "Treatment is most effective within 72 hours of symptom onset"; the Valtrex label says "most effective when started within 48 hours of the onset of rash" and has "no data on treatment initiated more than 72 hours after onset." For HZO, treatment "should not be delayed while awaiting definitive diagnosis or ophthalmology follow-up." IV acyclovir is used for immunocompromised, disseminated or CNS/orbital disease. Acyclovir is 85% renally excreted and can cause crystal nephropathy — keep patients hydrated ("Adequate hydration should be maintained for all patients") and reduce doses in renal impairment. Whether antivirals prevent PHN is disputed: StatPearls (zoster) says antiviral therapy "helps prevent postherpetic neuralgia," while StatPearls (PHN) finds "no clear evidence" they reduce PHN incidence.

Antiretroviral therapy is the disorder — it is started for everyone with confirmed HIV regardless of CD4 count or clinical stage, preferably within 7 days of diagnosis (per the DHHS, WHO and IAS-USA Panel 2024 recommendations, as reported by StatPearls), because early treatment reduces AIDS- and non-AIDS events, death from any cause, and onward transmission. A regimen combines 3 drugs from at least 2 classes, most often an integrase inhibitor with a dual NRTI backbone, chosen for speed of suppression and a low propensity to develop resistance. The one exception to starting immediately is a severe opportunistic infection, which is treated first to reduce the risk of IRIS. Adherence is the drug’s mechanism of durability: viral load rebounds within weeks of stopping, and the very high reverse-transcriptase error rate converts any gap into selected resistance — which is why nurses screen for the named barriers (pill-swallowing difficulty, shift work, unstable housing, substance use, fear of disclosure, lack of insurance) and offer pillboxes, blister packs, apps and alarms rather than simply restating the instructions. Two safety rules belong at the bedside: abacavir requires HLA-B*5701 pretesting and is contraindicated if positive, and magnesium, aluminum, calcium and iron supplements reduce absorption of dolutegravir, bictegravir and raltegravir — every antacid, supplement and new medication needs pharmacist review.

Recommended as soon as possible for anyone with suspected or confirmed flu who is hospitalized, has severe, complicated or progressive illness, or is at higher risk for complications — empirically, without waiting for a test. Best "ideally within 48 hours of symptom onset for the greatest clinical benefit," but still beneficial later in hospitalized, severe or progressive illness. Hospitalized patients and pregnant patients get oral oseltamivir; the course for uncomplicated flu is oseltamivir or inhaled zanamivir twice daily for 5 days, or a single dose of IV peramivir or oral baloxavir. Most healthy people with mild flu do not need them; when used, they shorten illness by about a day. Amantadine and rimantadine are not recommended because of resistance.

IV acyclovir is started empirically — never wait for confirmation — whenever HSV (or VZV) is suspected, especially with encephalitic features or immunocompromise: a delay beyond 48 hours worsens outcomes. Nursing owns the infusion safety: hydrate well and infuse over at least 1 hour (dilute < 7 mg/mL) to prevent crystalluria and nephrotoxicity, and watch the alkaline infusion for phlebitis and extravasation.

Zoster prophylaxis with bortezomib — "Patients receiving a bortezomib-containing regimen need prophylaxis for herpes zoster (usually with valacyclovir or acyclovir)."

Acyclovir for eczema herpeticum — "Prompt treatment with acyclovir can reduce morbidity."

Genital herpes sits at the edge of this page rather than inside it. It belongs to the same clinic visit and the same conversation, and a patient with one sexually transmitted infection is screened for the others — but the antiviral class page owns what these drugs do, when a course is episodic rather than suppressive, and what suppression achieves that symptom control cannot. Follow the link; this page carries none of it.

CMV prophylaxis — "Valcyte for CMV" in the first 3–6 months (StatPearls, kidney transplant).

The one class whose role changes with the letter. HAV and HEV: no antivirals — acute infection is supportive care only (ribavirin is used off-label for chronic HEV in the immunosuppressed and is contraindicated in pregnancy). Acute HBV: supportive unless severe — nucleos(t)ide analogs are reserved for bilirubin > 10 mg/dL, INR > 1.5–1.6, encephalopathy, or a protracted course. Chronic HBV: entecavir, tenofovir disoproxil, or tenofovir alafenamide (high barrier to resistance) suppress HBV DNA but do not cure — HBsAg loss is desired but rare — treatment is indefinite for HBeAg-negative and cirrhotic patients (AASLD 2018), and stopping can trigger a hepatitis flare, so ALT is monitored every 3 months for at least a year after any discontinuation; in pregnancy, third-trimester tenofovir for HBV DNA > 200,000 IU/mL further reduces transmission. HCV: an 8–12-week course of oral direct-acting antivirals cures more than 95% regardless of genotype (glecaprevir/pibrentasvir 8 weeks; sofosbuvir/velpatasvir 12 weeks), is recommended for nearly everyone with HCV including acute infection, and is confirmed by SVR — undetectable RNA 12 weeks after finishing; check HBV serology first because DAAs can reactivate HBV. HDV: nucleos(t)ide analogs do not work; peginterferon alfa is the off-label mainstay.

The original β-lactams — bactericidal cell-wall inhibitors. The defining nursing job is screening for and recognizing allergy, from rash to anaphylaxis.

β-lactam cousins of penicillin, organized by generation — each generation trades some gram-positive reach for broader gram-negative coverage.

Powerful, broad-spectrum DNA-synthesis blockers — but a boxed warning for disabling tendon, nerve, and CNS effects means they’re reserved when alternatives exist.

Powerful IV drugs for serious Gram-negative infection — but nephrotoxic and ototoxic. Levels matter.

Broad, generally safe protein-synthesis inhibitors — a penicillin-allergy alternative. Watch QT and CYP3A4.

Broad-spectrum 30S inhibitors. Generally avoided in pregnancy and in children 8 or younger (permanent tooth staining) unless the infection is serious — doxycycline is still first-line for Rocky Mountain spotted fever at any age — and kept apart from dairy/antacids.