Antivirals are medications that are used to treat infections caused by viruses. They are available in the form of pills, liquids, inhaled powders, and intravenous solutions for injection. In healthy people with normal immunity, many viral infections resolve spontaneously. However, treatment with antiviral medications can help minimize symptoms, reduce infectivity, and shorten the duration of the illness. Specific antivirals are used against specific viruses.

Antiviral medications act by inhibiting the replication of the virus. Meaning, they interfere with the life cycle of the virus and prevent it from multiplying. This ensures the viral load in your body (the number of virus copies present) does not reach a number that causes illness.

Unlike antimicrobial agents like antibiotics which destroy the microorganisms (bacteria), antivirals do not destroy the virus. It is difficult to develop antiviral drugs that can inhibit viral replication without harming the host cells (human cells). For this reason, although more than 200 human viruses have been discovered, antiviral medications are available only for a limited number of infections, such as influenza A and B, hepatitis B and C, herpes, and HIV.

Types of Viruses Treated with Antivirals

Antiviral medications are used to treat specific viral infections and are grouped according to the viruses they act against:

• RNA viruses like the influenza virus, hepatitis C virus, and respiratory syncytial virus
• DNA viruses like hepatitis B virus, human cytomegalovirus, human papillomavirus, herpes simplex virus, and varicella-zoster virus
• Retroviruses like the human immunodeficiency virus (HIV)

Antiviral Drugs

Influenza Viruses: Antivirals used to treat influenza viruses include M2 ion channel blockers like amantadine and rimantadine for influenza A and neuraminidase inhibitors like oseltamivir, zanamivir, and peramivir for the treatment of influenza A and B. These drugs help reduce symptoms if taken within 1-2 days of symptom onset. They may also be used as preventive medications in adults and children.

Herpes Viruses: Antiviral medications used to treat herpes virus infections include acyclovir, valacyclovir, penciclovir, and famciclovir. They are effective in people with active herpes infection. They have a selective action on cells infected with the virus and a minimal effect on healthy host cells. Therefore, these antivirals cause fewer side effects. Some antivirals used for herpes infections, such as ganciclovir and valganciclovir, have lower selectivity for infected cells and can therefore be more toxic. Additional antivirals like foscarnet, cidofovir, and fomivirsen are also available for herpes infections.

Hepatitis B Virus: Tenofovir, adefovir, entecavir, lamivudine, and telbivudine are used to treat chronic, active hepatitis B and HIV infections.

Hepatitis C Virus: Ribavirin, glecaprevir, grazoprevir, paritaprevir, simeprevir, voxilaprevir, daclatasvir, elbasvir, ledipasvir, ombitasvir, pibrentasvir, velpatasvir, dasabuvir, and sofosbuvir are some of the antivirals used for the treatment of hepatitis C.

Hepatitis B and C Viruses: Interferon-alpha and pegylated interferon-alpha are immunomodulatory drugs that inhibit viral protein synthesis and promote the breakdown of viral genetic material. They are used to treat chronic active hepatitis B and acute and chronic hepatitis C.

Human Immunodeficiency Virus (HIV): There are several FDA-approved antiretroviral drugs used to treat HIV, including:

• Nucleoside/nucleotide reverse transcriptase inhibitors (NRTIs) like abacavir, lamivudine, and zidovudine
• Non-nucleoside reverse transcriptase inhibitors (NNRTIs) like etravirine, efavirenz, delavirdine, and nevirapine.
• Integrase inhibitors like raltegravir and elvitegravir.
• Protease inhibitors like amprenavir, atazanavir, fosamprenavir, and nelfinavir.
• Entry inhibitors like enfuvirtide.
• Small molecule CCR5 antagonists like aplaviroc.

Antiretroviral drugs for HIV work by inhibiting various enzymes that are critical for HIV to multiply.

Over-the-Counter Antiviral Medications

Antivirals are not sold over the counter. You can only get them with a prescription from a healthcare provider. It is worth noting that many viral infections resolve spontaneously without specific antiviral treatment. Taking antiviral medications can cause serious side effects. Nonetheless, if you are sick with a viral infection, antivirals are an option. You should check with your doctor who may prescribe antivirals to treat your illness.

Common Side Effects of Antiviral Medications

Antivirals used to treat influenza A and B can cause nausea, vomiting, swelling, rash, headache, as well as upper and lower respiratory infections.

Antivirals used to treat herpes virus infections can cause side effects such as nausea, headache, confusion, burning or tingling sensations, and kidney problems. The effects on the kidneys can be prevented by ensuring adequate hydration and adjusting the dose.

The antiviral medications used to treat hepatitis B infection can cause side effects like headache, stomachache, fever, and nephrotoxicity (toxic effect on the kidneys). Antivirals used for hepatitis C infections can cause headache, nausea, diarrhea, stomachache, fatigue, insomnia, itching, rash, and skin allergies. Interferon-alpha used against hepatitis B and C viruses can cause flu-like symptoms, depression, seizures, and bone marrow suppression.

Antiretroviral drugs for HIV can cause many side effects, most commonly nausea, vomiting, diarrhea, dry mouth, headache, dizziness, difficulty sleeping, fatigue, rash, and pain.

Common Questions

Since antivirals are available to treat influenza, do I need to get the flu vaccine?

The flu vaccine helps prevent seasonal flu and its complications. Antiviral drugs are used to treat the flu. These medications are not a substitute for the flu vaccine. Everyone older than 6 months of age should get the flu vaccine each year. Antivirals can be used as a second line of defense should you get sick.

Why didn’t my doctor prescribe an antiviral for my stomach flu or common cold?

Unlike antibiotics that act against a wide range of bacteria (they are more broad-spectrum), antivirals tend to be more specific. There are more than 200 viruses that can cause the common cold, each one marginally different from the other, needing specific antiviral treatment. By the time your doctor has obtained a sample, tested it, and identified which virus is causing your cold or gastroenteritis, your symptoms, which are likely self-limited and short-lived, may already have resolved. It makes more sense, therefore, to manage the symptoms of your viral illness and let the virus die a natural death.

Can I get a discount on antivirals with BuzzRx?

Yes, you can get discounts on some medicines—including antivirals—as long as you have a signed prescription from your doctor.

References:

https://www.sciencedirect.com/topics/chemistry/antiviral-drug

https://cmr.asm.org/content/29/3/695

https://www.amboss.com/us/knowledge/Antiviral_agents

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3312400

https://www.cdc.gov/hiv/basics/livingwithhiv/treatment.html

https://www.cdc.gov/flu/treatment/whatyoushould.htm

https://www.epizone-eu.net/en/Home/show/FAQ-Antivirals.htm