Antiviral: What these drugs do and when to use them

Antivirals are medicines that fight viral infections by stopping viruses from replicating. They don’t work on bacteria, so antibiotics won’t help with the flu or COVID. Used at the right time, antivirals can cut symptoms, shorten illness, and reduce risk of complications. Timing matters: many work best when taken early in the infection.

Common antiviral drugs you should know

Tamiflu (oseltamivir) is widely used for seasonal flu; starting it within 48 hours of symptoms gives the best benefit. For herpes viruses, acyclovir, valacyclovir, and famciclovir help reduce outbreaks and speed healing. In recent years, COVID antivirals like remdesivir, paxlovid (nirmatrelvir + ritonavir), and molnupiravir became common options under medical guidance. Each drug targets a different step in the virus life cycle, so doctors pick based on the virus, how long you’ve been sick, and your health history.

Side effects vary. Tamiflu can cause nausea or headaches. Paxlovid may interact strongly with other meds because it includes ritonavir—always check drug interactions. Acyclovir is usually well tolerated but needs dose adjustments for kidney problems. If you feel dizzy, have severe nausea, allergic signs, or new breathing problems after starting a drug, contact your provider.

How to use antivirals wisely and buy them safely

Ask your doctor if an antiviral is appropriate. Don’t self-prescribe based on internet articles. If your doctor prescribes one, follow the exact dose and finish the course unless told otherwise. Store pills as instructed—some need room temperature, others refrigeration for suspensions.

Thinking about buying antivirals online? Use licensed pharmacies only. Check for a real prescription requirement, a physical address, and verified contact info. Avoid sites offering controlled meds without a prescription—those are risky and often counterfeit. If a deal looks too good, it probably is.

Not everyone needs an antiviral. For mild flu in healthy adults, rest, hydration, and OTC symptom relief (like acetaminophen for fever) may be enough. But if you’re pregnant, elderly, immunocompromised, or have chronic lung or heart disease, talk to a clinician quickly—antivirals can prevent serious complications.

Resistance is possible when antivirals are used improperly. That’s another reason to follow your prescriber’s plan. Finally, keep records of your medications and share them with any new provider to avoid harmful interactions.

If you want help checking a pharmacy or understanding a prescription, contact a pharmacist or your healthcare team. Quick questions can save a lot of trouble and keep treatment working as it should.