Valtrex (Valacyclovir) – Oral

What Is Valtrex?

Valtrex (valacyclovir) is a medication prescribed to treat certain viral infections, including chicken pox, cold sores, and other conditions caused by herpes viruses.

Valtrex is part of a class of antiviral drugs called nucleoside analogs. It prevents the viral growth of herpes by interfering with gene replication, the process in which a DNA molecule makes two copies of itself during cell division. This medication comes as a tablet that is taken by mouth.

What is Valtrex Used For?

The Food and Drug Administration (FDA) approved Valtrex for the following indications:

1. For ages 2 to 18: Chicken pox, a contagious infection caused by herpes varicella zoster virus
2. For ages 12 and older: Cold sores, usually caused by herpes simplex virus 1 (HSV-1)
3. For ages 18 and older:

• Genital herpes, usually caused by herpes simplex virus 2 (HSV-2)  
• Prevention of transmission of HSV
• Suppression of HSV
• Suppression of HSV for people who are immunosuppressed due to human immunodeficiency virus (HIV)
• Shingles, which is caused by reactivation of varicella zoster and produces a painful rash

The dosing of Valtrex differs for children and adults and is based on weight for the treatment of chicken pox. Valtrex is used short term for the treatment of chicken pox, shingles, and cold sores.

It can also be used for the short-term treatment of genital herpes or long term to suppress the virus and prevent transmission to a partner. However, it is important to remember that Valtrex will not cure your herpes infection completely.

How to Take Valtrex

Valtrex is a tablet that should be swallowed. You can take Valtrex with or without food. It is important to stay hydrated when using Valtrex.

If you are taking Valtrex for cold sores, chicken pox, shingles, or genital herpes, start treatment as soon as possible after your symptoms start. Initial signs of infection may include tingling, itching, or burning, or when the sore appears.

Storage

Store Valtrex tablets at a temperature of 59–77 degrees Fahrenheit. Keep the medication in its original container and away from children or pets.

Off-Label Uses

Valtrex has been used for the treatment of other antiviral conditions besides the approved indications, also known as “off-label” use.

Valtrex is sometimes prescribed for the off-label treatment of:

• Cytomegalovirus (CMV): This viral infection can be transmitted from a pregnant mother to a baby, potentially causing brain and/or liver damage to the baby. Valtrex has been prescribed for people who have CMV infection during pregnancy to reduce transmission to the baby.
• Bell’s palsy: This condition is characterized by temporary paralysis of one side of the face. It is believed to be associated with a reaction to a viral infection. Valtrex can sometimes be effective in treating Bell’s palsy.

What Are the Side Effects of Valtrex?

This is not a complete list of side effects, and others may occur. A medical professional can advise you on side effects. If you experience other effects, contact your pharmacist or a medical professional. You may report side effects to the FDA at www.fda.gov/medwatch or 800-FDA-1088.

Valtrex can cause several side effects, most of which are not dangerous. However, some serious side effects can occur.

Common Side Effects

Common side effects of Valtrex include:

• Headaches 
• Nausea 
• Abdominal pain

Headaches are the most common side effect that children experience when taking Valtrex. Be sure to discuss any side effects that you have with your healthcare provider and let them know if your symptoms worsen.

Severe Side Effects

Severe side effects caused by Valtrex can affect anyone. However, severe side effects are more common in older adults, people who take nonsteroidal anti-inflammatory medications (NSAIDs), including aspirin, Advil or Motrin (ibuprofen), and Aleve (naproxen sodium), and people who have kidney disease.

Some severe side effects associated with Valtrex include:

• Thrombotic thrombocytopenic purpura (TTP): This condition causes blood clots in the small blood vessels throughout the body, often with bruising. 
• Hemolytic uremic syndrome (HUS): This condition causes blood clots and bleeding throughout the body. 
• Acute kidney failure: Severe damage can cause the kidneys to rapidly stop functioning. Symptoms include dizziness, confusion, dark urine, a reduced amount of urine, or a complete lack of urine. This condition generally resolves with treatment. 
• Neurotoxicity: Nervous system effects can include agitation, hallucinations, confusion, delirium, seizures, and encephalopathy. These symptoms are expected to get better after Valtrex is stopped.

If you develop any signs of these problems, seek prompt medical attention.

Long-Term Side Effects

The effects of TTP and HUS can be fatal or may cause lasting organ damage.

Dosage: How Much Valtrex Should I Take?

Modifications

Having certain medical conditions may increase your risk of side effects or require that you take a lower dose.

Let your healthcare provider know if you:

• Have had a bone marrow transplant or kidney transplant
• Have advanced HIV disease, or AIDS
• Have kidney problems

Also, if you are aged 65 years or older you may need a lower dose of Valtrex.

For children who cannot swallow pills, your healthcare provider can prescribe Valtrex as an oral suspension. 

Talk to your provider if you become pregnant, are planning to become pregnant, or are breastfeeding. They will help determine the risks and benefits of taking this medication.

Missed Dose

Ask your healthcare provider how to proceed if you miss a dose of Valtrex. Generally, you can take your dose as soon as you remember that you missed it. Take your next dose at its regular time. However, do not take the missed dose if it is almost time for your next scheduled dose.

Overdose: What Happens If I Take Too Much Valtrex?

If you take too much Valtrex, it can lead to acute kidney damage. This is a medical emergency that can cause toxicity in your body and the inability to make urine.

Hemodialysis is a procedure that helps your body eliminate toxins and balance fluid—this may be necessary until your kidney function is restored.

Precautions

What Are Reasons I Shouldn’t Take Valtrex?

You should not take Valtrex if you are allergic to any of its ingredients or the antiviral medication acyclovir.

What Other Medications May Interact With Valtrex?

There are no clinically significant drug interactions with Valtrex.

What Medications Are Similar?

There are several antiviral medications that are similar to Valtrex but do not have identical approved indications. These include:

• Sitavig and Zovirax (acyclovir): This medication is available as a tablet or a liquid to be swallowed. It is also available in an injectable form to be used for severe HSV infections, including HSV encephalitis (brain infection). It is also available as a cream for the treatment of cold sores. 
• Famvir (famciclovir): This is available as a tablet for the treatment of cold sores, genital herpes, and shingles. 

Many other antiviral medications are used for treating different infections. For example, Epivir (lamivudine) and Viread (tenofovir) are used to treat HIV. Baraclude (entecavir) is used to treat hepatitis B.

How Can I Stay Healthy While Taking Valtrex?

There are several considerations that you must keep in mind to stay healthy while you are taking Valtrex: 

• Maintain hydration: Valtrex is more likely to cause kidney damage if you are dehydrated. 
• Pain control for shingles: Shingles can cause substantial pain. Your healthcare provider may prescribe a pain-control medication for you as your condition is resolving.
• Rest and fever control for chicken pox: Chicken pox infection can cause high fevers and sometimes fatigue. If your child has this infection, maintain rest, and follow their provider’s advice regarding management of fevers.

Herpes viruses are highly contagious, so it’s important to avoid infecting others while you are recovering.

Tips to avoid the spread of the following infections:

• Cold sores: Don’t share cups, utensils, lipstick, or kiss others while a cold sore is present 
• Genital herpes: Practice safe sex. 
• Chicken pox and shingles: Avoid contact with people who are immunosuppressed (such as due to cancer treatment or HIV), people who are pregnant, and babies until your infection has fully resolved.