Valacyclovir, sold under the brand name Valtrex, is a medication prescribed to treat herpes virus infections in both adults and children. While this antiviral drug effectively alleviates symptoms, it also carries potential side effects. Being aware of these effects and learning how to address them can assist you in the safe and proper usage of the medication. This article aims to provide insights into the side effects of Valacyclovir, ranging from common to severe, and advise on when to consult a healthcare professional.

Potential Valacyclovir Side Effects You Should Know

From common to severe side effects, Valacyclovir (Valtrex) can cause several reactions that you need to be mindful of.

Common Side Effects

Valacyclovir, also known as Valtrex, may trigger common side effects that are typically temporary, lasting for a few days or weeks before subsiding as the body adjusts to the drug. Should these effects intensify, persist for an extended period, or become bothersome, seeking medical advice is recommended. Some common side effects to watch out for include:

• Abdominal pain

• Runny nose

• Headache

• Nausea

• Dizziness

Mild Side Effects

These side effects are also temporary. However, if they become severe and bother you, consult the doctor. The mild side effects include:

Severe Side Effects

Valacyclovir, in rare cases, can lead to severe side effects that need immediate medical help:

• Kidney Problems: Kidney damage can occur with symptoms like bloody urine, swelling in the legs, ankles, and feet, weakness, or chest pain.

• Allergic Reactions: In some instances, individuals may experience severe allergic reactions characterized by symptoms like difficulty breathing, rapid heart rate, pronounced rash, lightheadedness, or swelling in the facial area, lips, or throat.

• Severe Skin Reactions: Peeling or blistering in the skin may occur which may need immediate medical attention.

• Central Nervous System Issues: The symptoms may include feeling agitated, trouble speaking, shakiness, confusion, or hallucinations, especially in older adults.

• Risk of Depression: Symptoms may develop like appetite and weight changes, sleep disturbances, fatigue, or lack of interest in activities.

Note: If severe side effects tend to seem life-threatening, call 911 immediately.

Side Effects of Valacyclovir on Children

The clinical trials reported the following side effects of Valacyclovir in children:

• Diarrhea

• Headache

• Nausea

• Fever

• Dehydration

• Runny nose

These reactions are mild and resolve on their own. If your child finds it bothersome and they last for a longer period, see the healthcare provider. 

Precautions When Using Valacyclovir

You should keep the following things into consideration when using Valacyclovir:

• Allergic to valacyclovir or acyclovir

A study says that individuals allergic to Valacyclovir, Acyclovir, or any of the ingredients of Valacyclovir should avoid it.

People with severe kidney impairment might require specific dosage adjustments or other treatments. So, they need to consult the doctors first.

People living with HIV/AIDS, or undergoing immunosuppressive therapy, should discuss this with their doctors.

• History of bone marrow or kidney transplant

Make sure to discuss if you ever have undergone bone marrow or kidney transplantation with your doctor to ensure safe use of the medicine.

People over 65 should contact the providers as they are at higher risk of experiencing some side effects. On the other hand, children under 12 should completely avoid it as it’s not recommended!

• Pregnant or breastfeeding

No evidence claims that valacyclovir can impact pregnancy or harm the baby, so talk with your gynecologist before planning to use it in the pregnancy or breastfeeding phase.     

Valacyclovir can interact with other drugs such as Aspirin, Tylenol, Benadryl, Lexapro, Ozempic, Xanax, Zofran, Zoloft, or Zyrtec. So, if you’re currently using any medication, tell your doctor about it as drug interaction may reduce the effectiveness of Valacyclovir and increase the risk of side effects. 

Tips to Safely Take Valacyclovir to Avoid Side Effects

Follow these tips to effectively and safely use Valacyclovir and avoid the risk of side effects:

• Use as prescribed: Follow the instructions for dosage and schedule of the medicine as prescribed by the doctor.

• Can take with or without food: Have it with food, in case of an upset stomach.

• Stay hydrated: Drink a lot of water for the proper functioning of the kidneys.

• Complete the course: Don’t stop taking the medication without consulting the doctor.

• Look for side effects: Report your unusual symptoms such as kidney issues or swelling to your doctor.

• Discuss your current medications: Make sure to inform any medicines you’re taking with your doctor to avoid interactions.

• Limit alcohol: Limit or avoid drinking alcohol as it can worsen side effects.

What to Do in Case of Overdose or Missed Dose

1. Overdose:

If you or someone else accidentally takes too much Valacyclovir, call 911 or Poison Control (800-222-1222) immediately.

2. Missed Dose:

Take the missed dose as soon as you remember unless it’s almost time for your next dose. In that case, skip the missed dose.

Important: Never double the dose to make up for a missed one.

When to Contact a Healthcare Provider?

It’s essential to seek medical attention if you experience any of the following:

• Severe allergic reactions: Trouble breathing, rashes, hives, or swelling in the face or throat.

• Kidney issues: Difficulty urinating, swelling in the legs, or less or no urine.

• Mental changes: Hallucinations, agitation, mood swings, or confusion.

• Severe stomach problems: Persistent vomiting, nausea, or stomach pain.

• Unusual weakness or tiredness: Feeling too weak or fatigued.

• Infection signs: Continuous sore throat, fever, or chills.

• Other concerning or unexpected symptoms: Any severe, unusual symptoms that are concerning you.

Final Thoughts

Though effective treatment for herpes virus infections, valacyclovir can bring certain side effects. The potential valacyclovir side effects from common (e.g. nausea, vomiting, or headache) to severe reactions (e.g. kidney damage or allergic reactions), can develop any symptoms. Though common, mild side effects can resolve in some days, severe ones may need immediate medical attention.

It’s crucial to always consult the doctor before starting valacyclovir treatment, especially if you are living with some medical condition or are on other medications. Also, regular monitoring is essential to lower the risk of side effects and understand whether the medicine is working as intended.

Frequently Asked Questions