A cold sore, also known as a fever blister, is an infection caused by the herpes virus. These sores can show up anywhere on the face but most often appear around the lips and nose.

While there are many treatments available for cold sores, oral antiviral medication can be one of the most effective ways to handle them. Here’s what you need to know about taking oral antiviral medication for cold sores. 

What Are Oral Antiviral Medications for Cold Sores?

Oral antiviral medications are prescription drugs that fight against the virus that causes cold sores – Herpes Simplex Virus (HSV). These medications prevent the virus from replicating and spreading throughout your body while also reducing symptoms associated with cold sores. 

You can also check our article on Are Some People Immune to Cold Sores?

Types of Oral Antiviral Medication for Cold Sores

The three most common types of oral antivirals used to treat cold sores are Acyclovir, Valacyclovir, and Famciclovir.


Acyclovir is available in both generic and brand-name formulations, but it is not as effective as Valacyclovir or Famciclovir in treating cold sores. 


Valacyclovir is more easily absorbed by the body than acyclovir which makes it a better choice if you want an effective treatment plan.


Lastly, Famciclovir is a prodrug which means it needs to be broken down by the body before it can be used as an antiviral medication. It has been shown to be more effective than either Acyclovir or Valacyclovir in treating cold sores. 

How Do They Work? 

All three of these medications work in similar ways. They interfere with the virus’s ability to replicate itself so that it cannot spread throughout your body or cause further damage.

This helps reduce the symptoms associated with a cold sore outbreak, such as pain and itching, while also reducing the duration of an outbreak by several days or even weeks. 

Dosage and Duration

The dosage and duration of your treatment will depend on several factors including your age, weight, health condition, and severity of your symptoms. Your doctor will prescribe the right dosage for your particular case.

Generally speaking, these medications should be taken for 7-10 days in order to be fully effective against the virus that causes cold sores. 

When Should I Take Oral Antivirals? 

Oral antiviral medications should be taken at the first sign of an outbreak, typically within 72 hours or when you feel tingling or burning on your lips or around your mouth.

Taking these medications within this timeframe has been clinically proven to reduce the duration and severity of an outbreak. 

Benefits of Taking Oral Antiviral Medication for Cold Sores

Reduces Symptoms

Taking an oral antiviral medication can help reduce the severity of symptoms associated with cold sores. This might include reducing pain, discomfort, redness, swelling, inflammation, and healing time.

If taken early enough—within 24 hours of noticing symptoms—the medication can even help to prevent outbreaks from occurring in the first place. This can be especially helpful for those who tend to get frequent cold sores. 

Prevents Future Outbreaks

Another benefit of taking an oral antiviral medication for cold sores is that it helps prevent future outbreaks from occurring.

This is especially beneficial if you routinely suffer from recurrent outbreaks or if you are particularly prone to getting cold sore flare-ups due to environmental factors such as high stress levels or too much exposure to sunlight.

Taking daily doses of an oral antiviral medication will help keep your immune system strong while helping avoid any potential triggers that could lead to further outbreaks down the line.

Decreases Risk of Transmission

Finally, taking an oral antiviral medication for cold sores can greatly reduce your risk of transmitting the virus to others since it helps prevent new outbreaks from occurring in the first place.

Additionally, if you do experience a flare-up despite taking the medication regularly, applying topical ointments or creams containing antiviral ingredients will help minimize any potential risk involved with spreading HSV-1 through direct contact with another person’s skin or bodily fluids such as saliva or tears. 

Side Effects and Precautions to Consider When Taking Oral Antiviral Medication for Cold Sores

Common Side Effects

The most common side effects of oral antivirals may include nausea, vomiting, diarrhea, headache, or dizziness. If you experience any of these symptoms after taking an antiviral medication for a cold sore, contact your doctor immediately.

In rare cases, more serious side effects such as chest pain or difficulty breathing can occur and should be reported immediately. 

Interactions with Other Medications

It’s important to tell your doctor about all medications you’re currently taking before beginning treatment with an antiviral medication for cold sores.

Some drugs have been known to interact with certain antivirals in a way that could cause serious medical complications. For example, some antibiotics can interfere with certain antivirals and increase the risk of liver damage or kidney failure if taken together. 

Contraindications for Certain Individuals

Some people should not take oral antivirals for cold sores because of their individual health conditions or allergies. People who have kidney disease or impaired renal function should not take these medications since they can cause further damage to the kidneys.

Additionally, those who are allergic to any ingredient in the medication should avoid taking it as well as those who already have a weakened immune system due to another condition such as HIV/AIDS. 

Precautions to Take Before Taking Medication

Before taking any oral antiviral medication, it’s important to talk with your doctor about possible risks and benefits associated with the drug so that you can make an informed decision about whether or not it is right for you. 

Some people may need a lower dose of the drug, while others may need more frequent monitoring when taking certain medications due to their individual health history or other factors such as age or weight. Your doctor will be able to tell you what precautions you should take before starting any new medication. 


Taking oral antiviral medication for cold sores can be an effective way to treat a cold sore outbreak quickly while minimizing symptoms such as itching and pain. However, it’s important to remember that these medications do come with potential risks and side effects, so it’s best to consult with your doctor before beginning any kind of treatment plan, especially if you have any underlying health conditions. 

With proper guidance from a healthcare provider, as well as diligent adherence to dosing instructions, you can safely use an oral antiviral medication to help manage your cold sore outbreaks quickly and effectively!