Valtrex - Medicine for Cold Sores

By ,  Valtrex

Valtrex is an antiviral drug, that goes by the generic name - Valacyclovir. It is used to treat infections like genital herpes, cold sores, and shingles caused by certain herpes viruses. In children, Valtrex is primarily used for treating cold sores and chickenpox. In adults, Valtrex is given to treat shingles and cold sores around the mouth. It is also given to prevent genital herpes, and it doesn't cure herpes. Valtrex is easily available online in the generic or branded version with a doctor's prescription.

Cold sore and treatment with Valtrex

Cold sores, commonly known as the fever blister are caused by the herpes simplex virus. These are the small, fluid-filled tumors formed near and around mouth and lips causing itching and burning sensation. Valtrex is often practiced to treat herpes viruses. There are 2 types of herpes viruses - herpes simplex and herpes zoster. And herpes simplex causes cold sores, whereas the herpes zoster produces shingles. The sores can be formed in and around the mouth like the cold sores, or around genital called genital herpes. Valtrex fights the viruses causing the infection and doesn't not sure the infection. Valtrex works against the virus and prevents it from growing and spreading. 

The dosage of Valtrex?

Valtrex is an oral drug, which comes in 2 forms - 500mg and 1gm. It is important to take this medicine as instructed by the doctor, especially the dosage and duration of the treatment. The dosage and medicine continuation depend on the severity of the infection, medical condition and patient's response to the drug. 

  • In adults and children above 12 years, the normal recommendation would be to take 2gms daily twice. And Valtrex should be taken orally at the earliest signs of the cold sore.  
  • In children below 12 years, Valtrex is not recommended. However, Valtrex is used to treat chickenpox, caused by varicella-zoster in children above 2 years. 

It is important to take Valtrex at the beginning or the first sign of cold sore for better results. Follow the doctor's instruction, do not take overdosage or less than prescribed. 

Side Effects of Valtrex

The most common side effects of Valtrex are - headache, dizziness, vomiting, nausea and stomach pain. Valtrex is a very strong drug when taken more than prescribed, it can cause some serious damage to the patient's body. Some of the serious side effects of Valtrex are:

  • Kidney damage: The patient might get a fever, abdominal pain, and pain during urination.
  • Depression and nervous system problems: The patient may show aggressive behavior, suffer hallucination, unsteady movements and speech problems.
  • Allergic reactions: Rashes, swollen mouth, and throat, and sometimes breathing difficulty.

In such cases, where the patient shows serious side effects, it is important to immediately visit the doctor for help. 

When to avoid Valtrex?

Valtrex is not meant for all patients. A patient suffering from kidney problems must take a lower dosage of Valtrex. And Patients allergic to acyclovir or the ingredients of Valtrex must consult with a doctor before taking Valtrex. 


Cold sores don't need any medications, they start to heal over time, however, if the virus stays in the patient's body, cold sores may return and the occurrences increase. Fighting the virus and preventing it from growing and spreading can be done by taking Valtrex. Valtrex being a strong drug, it is important to always consult a doctor before taking Valtrex for cold sores.