What is Valacyclovir?
Valacyclovir is a prescription-only oral antiviral medication, approved by the FDA for the treatment of Herpes simplex outbreaks. Valacyclovir is one of the most commonly prescribed antiviral drugs, used to treat both types of the virus - HSV-1 (responsible for cold sores) and HSV-2 (responsible for genital herpes).
Valacyclovir works by slowing down the replication of the virus within your body. While it doesn’t get rid of the Herpes virus, it does drastically slow down its growth, allowing your body to better fight the infection. This means that the severity of your infection will be greatly reduced, and you will be less likely to transmit the virus to others.
Compared to other anti-viral drugs, Valacyclovir has a higher bioavailability, which means that a greater volume of the drug is absorbed into the body, increasing its efficacy.
How should I take Valacyclovir tablets?
Valacyclovir tablets are available from Seven Cells in the form of tablets, containing 500mg and 1000mg of the active ingredient Valacyclovir Hydrochloride. You should take one tablet daily, and your physician will discuss these dosage details with you during your consultation. The length of your treatment will depend upon the severity of your infection, and this will be determined during your medical assessment. You can take these tablets with or without food.
You should take your Valacyclovir tablets regularly. If you do happen to miss a dose, don’t worry, just take it as soon as you remember and carry on with your next dose at the regular time. However, if it is nearly time for your next dose, just skip the missed tablet.
Valacyclovir is available in two doses, 500mg, and 1000mg tablets. Valacyclovir may be used differently for different indications, here we summarize some of these uses. It is important to note that dosages may need to be adjusted to account for chronic conditions, such as kidney problems. You should take valacyclovir as instructed by your doctor.
To abort an outbreak:
Valacyclovir should be taken as soon as you notice any signs or symptoms of herpes infection. There is currently no evidence available to support its efficacy once symptoms are visible. At the start of an outbreak, you may notice burning, tingling, itching, or other localized sensations.
You should take two 1000mg valacyclovir tablets (for a combined dose of 2000mg), followed by a further two 1000mg tablets 12 hours later. Keep hydrated by drinking plenty of fluids throughout the day. For HIV-infected patients, the recommended dose is one 1000mg tablet every 12 hours for 5 to 10 days.
Valacyclovir has not been approved for the suppressive treatment of oral herpes, however, physicians may use their discretion to prescribe it off-label if they believe it to be the most appropriate course of treatment. Your doctor will take into account your individual medical history, symptoms, and preferences when making this decision.
If your doctor decides to prescribe valacyclovir for the suppression of oral herpes, they may recommend that you take one 500mg or one 1000mg tablet once daily.
To abort an outbreak:
To stop an outbreak of genital herpes in its tracks, the FDA recommends that patients take one 1000mg valacyclovir tablet twice daily for 10 days. This treatment should start as soon as lesions or symptoms are noted and preferably within 48 hours of the attack.
The CDC advises that the same dose should be used for 7 to 10 days, stating that “treatment may be extended if healing is not complete after 10 days.”
HIV-infected patients should take one 1000mg tablet every 12 hours for 5 to 14 days.
Treatment of recurrent genital herpes (including HIV-infected patients):
As soon as signs or symptoms of an outbreak are noted, and preferably with 24 hours of onset, the FDA recommends using one 500mg valacyclovir tablet twice daily for 3 days. The same dosage is recommended by the CDC, but they also recommend an alternative dosage of one 1000mg tablet once daily for 5 days.
For HIV-infected patients, the recommended dosage is one 1000mg valacyclovir tablet every 12 hours for 5 to 14 days.
If less than 10 outbreaks are experienced each year, patients may be recommended to take one 500mg valacyclovir tablet once daily. If more than 10 outbreaks occur yearly, patients may be advised to take one 1000mg tablet once daily.
For the prevention of transmission between partners:
To reduce the risk of transmission between partners, the infected partner should take one 500mg valacyclovir tablet once daily. There is strong evidence to support the efficacy of this regimen, however, this typically refers to patients who experience 9 or fewer outbreaks each year.
How long does it take for Valacyclovir to work?
It is difficult to say for sure how long Valacyclovir tablets will take to have an effect, as this depends on the severity of your infection and how quickly you initiate treatment. Once in the bloodstream, valacyclovir will get to work straight away. If you take the tablets promptly after noticing the first symptoms of infection, you should notice an improvement in around 2-3 days.
As it targets the process of DNA replication, valacyclovir will only attack actively reproducing viruses. This means that it will work quickly to treat an active infection, but will have no effect on inactive viruses that are hiding within the nervous system. Taking valacyclovir regularly may help to reduce outbreaks of herpes infections by 70 to 80% and reduce transmission between partners by around 50%.
If taken at the earliest signs of an outbreak, valacyclovir may abort the attack or shorten its effects. The earlier you initiate valacyclovir treatment, the better.
While valacyclovir starts to target the herpes virus within hours of taking it, visible symptoms may take several days to start to heal, and the virus can remain active during the healing process.
Are there any side effects?
Most people tolerate Valacyclovir tablets very well, as long as they are taken correctly. However, as with all medication, there is a risk of developing some adverse effects.
A very common side effect (may affect more than 1 in 10 people) is a headache.
Common side effects (these may affect up to 1 in 10 people) include nausea, vomiting, diarrhea, photosensitivity (skin reaction after sun exposure), rash, and itching.
Uncommon side effects (these may affect up to 1 in 100 people) include confusion, hallucinations (seeing and/or hearing things that are not there), drowsiness, tremors and feelings of agitation. These adverse effects involving the nervous system typically occur in the elderly, patients with kidney problems, or in organ transplant patients when taking high doses of valacyclovir at 8 grams or more daily. Stopping or reducing this dose should alleviate these symptoms.
Other uncommon adverse effects include shortness of breath, an itchy, hive-like rash (urticaria), stomach pain, kidney pain in the lower back, and blood in the urine.
Rarely, valacyclovir may cause abnormalities in blood tests including a reduction in the number of platelets (thrombocytopenia), a reduction in the number of white blood cells (leukopenia), or an increase in substances that the liver produces.
Rare side effects (may affect up to 1 in 1000 people) include a lack of coordination and unsteadiness on the feet (ataxia), a slow and slurred speech, fits, altered brain function, loss of consciousness, confused or disturbed thoughts. As with the nervous system adverse effects discussed above, these side effects are also more likely to affect the elderly, patients with kidney problems, or in organ transplant patients when taking high doses of valacyclovir at 8 grams or more daily. Stopping or reducing the dose should alleviate these symptoms.
Rarely (may affect up to 1 in 1000 people) valacyclovir can cause kidney problems that result in little or no urine being passed.
Side effects are typically mild, and you can help to limit them by staying well hydrated. If any of these symptoms persist, or you have any concerns, be sure to contact your doctor. A comprehensive list of all known side effects of valacyclovir can be found in your package insert.
Valacyclovir treatment rarely causes severe allergic reactions. Signs of a severe allergic reaction include flushing, an itchy skin rash, swelling of the lips, face neck and throat which may result in difficulty breathing, and a fall in blood pressure which may lead to collapse. If you experience any of these warning signs, then you should seek emergency medical treatment immediately.
Valacyclovir vs. Acyclovir
Initially approved by the FDA for the treatment of herpes simplex infections in 1985, Acyclovir, under the brand name Zovirax®, was the first antiviral drug approved in this category. The sticking point with acyclovir is that it is slowly and poorly absorbed from the digestive tract, with only 10-20% reaching the bloodstream. While increasing the dosage may seem like the answer, this results in even less absorption of the drug. To achieve therapeutic doses of acyclovir within the blood, patients may be required to take up to five doses daily.
Valacyclovir is a prodrug of acyclovir, meaning that it is converted into acyclovir once in the body. Valacyclovir is absorbed much more efficiently than acyclovir, with around 54% reaching the bloodstream. This means that doses can be spaced less frequently, while still achieving excellent treatment results. Depending on the indication, valacyclovir is taken 1 to 3 times daily, whereas acyclovir is used 2 to 5 times daily. Due to its easier dosing schedule and high efficacy, valacyclovir is generally favored by both doctors and patients.