Valaciclovir is an antiviral medicine which means it is designed to act against viruses. It is specifically designed to treat the herpes simplex virus that causes cold sore symptoms. Valaciclovir is classified as a pro-drug, which means it converts into another drug (Aciclovir) when it enters the body.
Valaciclovir works by interrupting the normal process of viral replication – when viruses copy themselves inside your cells. This helps reduce the number of viruses in your body and in turn helps reduce the severity of symptoms experienced. Since the virus reproduces very early in the infection, you will benefit most from treatment if you take Valaciclovir Tablets as soon as the first symptoms appear, ideally within 5 days of their appearance.
This medication does not cure cold sores as the virus continues to live in the body even after an outbreak, but it works to reduce the severity and length of the outbreak whilst decreasing the risk of transmitting the virus to other people. Valaciclovir starts working almost immediately after you start taking it and is effective in reducing the healing time and reducing the risk transmitted to other people.
Valaciclovir is an oral medication that comes in 500mg tablet formulation. The usual dose of Valaciclovir for the treatment of cold sores is one tablet twice a day with water for 5 days. The treatment is most effective when you use it at the first signs of cold sore symptoms (i.e. visible blisters and a burning sensation). It is important to remain hydrated during the course of your treatment to minimise the risk of dehydration. Whilst alcohol is not prohibited whilst taking this medication, it is important to limit consumption to allow the medication to work properly.
How quick and well Valaciclovir works will depend on the severity of your symptoms and how soon you notice the symptoms before starting treatment. As soon as you start to notice the symptoms, it is best to start taking Valaciclovir.
Valaciclovir is usually more convenient to fit into a patient’s daily lifestyle due to its lower dosing interval.
Always use this medication exactly as your clinician has told you. Check with our clinical team or your GP or pharmacist if you are not sure.
Medicines and their possible side effects can affect individual people in different ways. The following are some of the side effects that are known to be associated with this medicine. Just because a side effect is stated here, it does not mean that all people using this medicine will experience that or any side effect. While it is generally well-tolerated, it can have several side effects. Here is a detailed overview of the potential side effects associated with valaciclovir:
Common Side Effects
- Nausea: Some patients may experience feelings of nausea while taking valaciclovir.
- Headache: Headaches are a frequently reported side effect.
- Diarrhea: Gastrointestinal upset, including diarrhea, may occur in some individuals.
- Dizziness: Patients can experience lightheadedness or dizziness while on this medication.
- Fatigue: Some individuals report feeling unusually tired or fatigued after starting the medication.
Less Common Side Effects
- Rash: Skin rashes may develop, ranging from mild to severe.
- Abdominal Pain: Mild abdominal discomfort can occur as a side effect.
- Increased Liver Enzymes: Liver function tests may show elevated liver enzymes during treatment, indicating potential liver stress.
- Cramps or Muscle Pain: Some patients report muscle cramps or general muscle pain while using valaciclovir.
Rare Side Effects
- Neurotoxic Effects: High doses or renal impairment can lead to neurological side effects,including confusion, tremors, hallucinations, and, in rare cases, seizures.
- Renal Impairment: Valaciclovir can affect kidney function, particularly in patients with pre-existing kidney conditions. Renal impairment may lead to elevated blood urea and creatinine levels.
- Thrombocytopenia: Some individuals may experience a decrease in platelet count, leading to increased bruising or bleeding.
- Hemolytic Uremic Syndrome (HUS): Although extremely rare, patients may develop HUS, a serious condition that can lead to kidney failure and low platelet counts.
For full information on side effects and correct use, see the patient information leaflet. If any side effects concern you, or you are experiencing any of the side effects mentioned in the patient information leaflet whilst taking this medication, please contact our clinical team or speak to your GP.
If you have a damaged or weakened immune system (immunocompromised) you should seek medical advice before taking Valaciclovir and at any time you experience a cold sore or other infection.
If you are elderly, renally impaired, pregnant or breastfeeding, you should seek medical advice before taking aciclovir.
In rare cases, some side effects will require immediate medical attention. These include:
- Signs of kidney problems, such as urinary changes and back/side pain
- Mood changes, including agitation, confusion and hallucinations
- Shaky or unsteady movement
- Difficulty speaking
- Signs of a severe allergic reaction, including rash, itching, swelling, severe dizziness and trouble breathing
Get emergency medical help if you have signs of an allergic reaction to this medication. These include:
- Hives
- Dizziness
- Fast or pounding heartbeats
- Wheezing
- Difficult breathing
- Swelling of your face, lips, tongue, or throat.
It is important that you let us know which prescription, over-the-counter medicines and recreational drugs you are currently taking. You must also tell us about any other medical conditions that you currently have (or had in the past). This will help us ensure the prescribed medication is safe and appropriate for you to take.
For full information on warnings, medication interactions and contraindications, refer to the Patient Information Leaflet. Please read all packaging and the Patient Information Leaflet before taking any new medicine and inform our clinical team or your GP of medicines you are taking or intend to take.
