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acyclovir vs baloxavir marboxil

Side-by-side comparison of acyclovir and baloxavir marboxil Data from FDA drug databases (Orange Book, NDC Directory, recalls, shortages) covering 20,000+ approved drugs, plus CMS pricing; see our methodology.

Drug Class
acyclovir Antiviral (Nucleoside Analog)
baloxavir marboxil Endonuclease Inhibitor (Antiviral)
Type
acyclovir Prescription
baloxavir marboxil Prescription
Summary
acyclovir

Acyclovir is an antiviral medicine. It is used to treat infections caused by certain viruses.

baloxavir marboxil

Xofluza is an antiviral medicine that can treat the flu. It can also prevent the flu if you have been around someone who is sick.

What It Treats
acyclovir

Acyclovir is used to treat shingles, which is caused by herpes zoster. It also treats genital herpes, both the first time you have it and when it comes back. Acyclovir can also treat chickenpox.

baloxavir marboxil

Xofluza is used to treat the flu in people 5 years and older. You must have had flu symptoms for no more than 48 hours. It can also be used to prevent the flu after you have been in contact with someone who has the flu. Keep in mind that the flu virus can change over time, so Xofluza may not always work.

How It Works
acyclovir

Acyclovir stops the virus from growing and spreading. It does this by interfering with the virus's ability to make copies of itself. This helps your body fight off the infection.

baloxavir marboxil

Xofluza stops the flu virus from making more copies of itself in your body. It does this by blocking a protein the virus needs to grow. This helps you get better faster or prevents you from getting sick.

Common Side Effects
acyclovir
  • Malaise (feeling unwell)
  • Nausea
  • Diarrhea
baloxavir marboxil
  • Diarrhea
  • Bronchitis
  • Nausea
  • Sinusitis
  • Vomiting (in children)
FAERS Reports
acyclovir
  • Tiredness 7,612
  • Diarrhea 7,064
  • Using the medicine for something it's not approved for 5,797
  • Lung infection 5,474
  • Feeling sick to your stomach 5,330
baloxavir marboxil
  • No Adverse Event 518
  • Off Label Use 419
  • Intentional Product Use Issue 283
  • Diarrhoea 129
  • Vomiting 120
Serious Warnings
acyclovir

Acyclovir can cause nervous system problems, especially in older adults or people with kidney problems. Tell your doctor if you have kidney problems before taking this medicine.

baloxavir marboxil

Xofluza can cause allergic reactions like anaphylaxis. Get medical help right away if you have trouble breathing, hives, or swelling. Xofluza is not for children under 5 years old because it may not work as well in this age group. Xofluza does not prevent bacterial infections, which can happen with the flu. See a doctor if you think you have a bacterial infection.

Pregnancy
acyclovir

Tell your doctor if you are pregnant or plan to become pregnant. It is not known if acyclovir will harm an unborn baby. Talk to your doctor about the risks and benefits of taking acyclovir while breastfeeding.

baloxavir marboxil

Tell your doctor if you are pregnant or plan to become pregnant. The benefits of taking Xofluza should be weighed against any potential risks to the baby. It is not known if Xofluza passes into breast milk. Talk to your doctor about the best way to feed your baby if you take Xofluza.

Also Compare — Nearby Drugs

How to Read This acyclovir vs baloxavir marboxil Comparison

acyclovir is classified in the Antiviral (Nucleoside Analog) drug class, while baloxavir marboxil sits within the Endonuclease Inhibitor (Antiviral) class. Drugs from different classes work through distinct mechanisms, so a head-to-head comparison illustrates trade-offs rather than equivalence. Both drugs are prescription-only, so a licensed provider must authorize use.

Adverse event totals above are pulled from the FDA's Adverse Event Reporting System (FAERS). For these top-ranked reactions alone, acyclovir has 31,277 submissions while baloxavir marboxil has 1,469. Those figures reflect cumulative reporting volume — not per-patient risk — so older, widely dispensed drugs typically look worse on count alone. No direct interaction between these two drugs is listed in our FDA-derived dataset, though co-prescription still warrants pharmacist review. Serious warnings, pregnancy guidance, and contraindications can differ even when indications overlap.

A table cannot substitute for clinical judgment. Effectiveness, tolerability, drug-drug interactions with your other medications, kidney and liver function, pregnancy status, insurance formulary, and price all feed into a decision that only a licensed prescriber can make responsibly. Data here is sourced from FDA Structured Product Labels (SPL) and FAERS, both of which update as manufacturers and clinicians submit new information. This page is for educational purposes only, is not medical advice, and should not be used to self-switch between acyclovir and baloxavir marboxil — always consult your physician or pharmacist first.

Important: This comparison is for informational purposes only. Drug effects vary between individuals. Always consult your doctor or pharmacist for personalized medical advice.