Valacyclovir (Valtrex) in Canada: Uses, Dosage, and How to Get a Prescription

If you’ve just been handed a prescription for valacyclovir — or you’re wondering whether to ask for one — you’ve probably got a few questions. Some of the most common are: Is valacyclovir the same thing as Valtrex? Will it actually get rid of a cold sore? And can you get valacyclovir without going to a clinic?

The short version is that valacyclovir and Valtrex are the same medicine. Valacyclovir is the drug name, Valtrex is the original brand name. It’s one of the most commonly prescribed antiviral treatments in Canada for cold sores, genital herpes, and shingles. Valacyclovir is well tolerated for most people, and it usually works best when started early.

In this article, we cover what valacyclovir is, how it works, and the typical doses for the conditions it treats. We also look at the side effects worth knowing about, and how to get valacyclovir in Canada.

What Is Valacyclovir (Valtrex)?

Valacyclovir is an antiviral medication that treats infections caused by the herpes family of viruses — the ones behind cold sores, genital herpes, shingles, and chickenpox. In Canada, it’s available by prescription only, usually taken as a short course of tablets during an outbreak.

Valtrex is simply the original brand name of the medication. When a doctor prescribes “valacyclovir,” that’s the active ingredient; when they say “Valtrex,” they mean the same molecule sold under GlaxoSmithKline’s brand. In Canada, you’ll most often be dispensed a generic version, which contains the identical active ingredient. It comes as a tablet in two strengths, valacyclovir 500 mg and valacyclovir 1,000 mg (1 gram).

One important point up front: valacyclovir manages the herpes viruses, it doesn’t cure them. These viruses stay in the body for life and can reactivate, so the medication’s role is to shorten outbreaks and ease symptoms when they happen. Some people may be prescribed valacyclovir every day as ongoing “suppressive” therapy — most often those with frequently recurring genital herpes — which can cut recurrences substantially and lower the risk of passing the virus to a partner.

Is Valacyclovir an Antibiotic?

Valacyclovir is an antiviral, not an antibiotic. Antivirals and antibiotics are not interchangeable. Antibiotics are prescribed to treat bacterial infections, while antivirals treat viral infections. If you’ve been prescribed valacyclovir, it’s because your doctor believes a viral infection is involved (which an antibiotic probably wouldn’t help with).

Valacyclovir vs. Acyclovir

You may see valacyclovir mentioned alongside acyclovir (brand name Zovirax), and the two are closely related. Valacyclovir is a prodrug of acyclovir: an inactive form that your body converts into acyclovir once you take it. Acyclovir is the drug that actually does the work — valacyclovir is just an easier-to-absorb way of delivering it.

Taken on its own, acyclovir is absorbed poorly. Only about 10 to 20 percent of a dose reaches your bloodstream, compared to 54 percent of valacyclovir. Because so much more valacyclovir is absorbed, you can take it once to three times a day, versus up to five times a day for oral acyclovir. The two are otherwise comparably effective. Valacyclovir’s advantage over acyclovir is simply that it’s easier to keep up with.

How Does Valacyclovir Work?

Valacyclovir works by stopping the herpes virus from multiplying. Once it’s in your body, it becomes acyclovir, the active form of the drug. Acyclovir only switches on inside cells that are already infected with a herpes virus, meaning it targets the infection while largely leaving healthy cells alone.

Once active, acyclovir blocks the machinery the herpes virus uses to copy its own DNA. Without new copies, the virus can’t spread to other cells, which gives your immune system the upper hand and lets the affected skin heal. Put simply, valacyclovir doesn’t destroy the herpes virus outright — it halts the outbreak so your body can recover.

What Does Valacyclovir Treat?

Health Canada has approved valacyclovir for several specific uses, each involving a virus from the herpes family.

Cold Sores (Oral Herpes)

Cold sores are caused mainly by herpes simplex virus type 1. Valacyclovir for cold sores is approved in adults and adolescents 12 and older, and it works best the earlier you start treatment. Taking it at the first tingle or itch, before a blister appears, can shorten the outbreak and ease the discomfort. See our guide on how to treat cold sores for more information.

Genital Herpes

Valacyclovir is approved to treat genital herpes. It may be prescribed for a short period to manage outbreaks or on an ongoing basis to suppress them. Suppressive treatment can reduce how often outbreaks happen and lower the risk of passing the virus to a partner. It doesn’t remove the risk entirely, though. Herpes can still spread between outbreaks through what’s called asymptomatic shedding, so precautions matter.

Shingles (Herpes Zoster)

Shingles is caused by the same virus behind chickenpox (varicella-zoster), reactivating later in life. It usually presents as a painful, blistering rash in a band on one side of the body. Valacyclovir for shingles is a treatment approved by Health Canada. As with cold sores, the sooner you start treatment the better, ideally within 72 hours of the rash appearing.

One Canada-specific note: unlike in the United States, where the FDA also approves valacyclovir for chickenpox in children, Health Canada hasn’t authorized a chickenpox indication or any use in children under 12. If a doctor recommends it outside the approved Canadian uses, that’s an off-label decision they’ll discuss with you directly.

Valacyclovir Dosage

The right dose of valacyclovir depends on which condition is being treated and the individual’s medical history. With that in mind, the figures below are the standard regimens your doctor will typically work from, not a prescription to self-manage (note: Valtrex dosage is identical to generic valacyclovir).

The standard adult doses of valacyclovir in Canada are as follows:

• Cold sores: 2 grams (two 1,000 mg tablets) taken twice in a single day — one dose at the first sign of symptoms and a second about 12 hours later. Treatment is only one day, and taking it longer doesn’t add benefit.
• First genital herpes outbreak: 1 gram twice daily for 10 days.
• Recurrent genital herpes: 500 mg twice daily for 3 days, started at the first symptom.
• Daily suppression: 500 mg to 1 gram once daily, depending on how frequent outbreaks are.
• Reducing transmission: 500 mg once daily for the partner who carries the virus, combined with safer-sex practices.
• Shingles: 1 gram three times daily for 7 days, started within 72 hours of the rash. 

If you have reduced kidney function, your doctor will usually lower the dose, because valacyclovir is cleared through the kidneys. 

Patients often ask if they should double up a cold-sore dose or extend treatment to try to clear an outbreak faster. The cold-sore regimen is already a deliberately high, short burst, and going beyond it raises the risk of side effects without improving results. If you miss a valacyclovir dose or the course doesn’t seem to be working, that’s a conversation for your doctor or pharmacist, not a reason to take extra.

How Long Does Valacyclovir Take to Work?

Valacyclovir starts absorbing within a couple of hours, but it doesn’t work instantly. 

For cold sores, a one-day course of valacyclovir treatment was shown in a randomized trial to shorten the average outbreak by about a day compared with placebo (most noticeable when treatment begins within hours of the first tingle). 

For genital herpes and shingles, expect gradual improvement over the first few days, as pain eases and lesions begin to crust and heal. The earlier you start, the more effective treatment tends to be.

Side Effects of Valacyclovir

The most common valacyclovir side effects are:

• Headache
• Nausea
• Stomach or abdominal pain

The list above also includes Valtrex side effects. If experienced at all, side effects of valacyclovir or Valtrex are usually mild, tend to pass on their own within a few days, and are more likely at the higher doses used for suppression. 

Less commonly, people report dizziness, vomiting, fatigue, or a rash.

Serious Side Effects and Warnings

Serious reactions to valacyclovir are rare, but worth being aware of. 

At very high doses, or in people who are older, dehydrated, or have reduced kidney function, valacyclovir can occasionally cause neurological effects such as confusion, agitation, or hallucinations, and in rare cases may affect the kidneys. Staying well hydrated while taking valacyclovir is a sensible precaution.

Important safety note: Stop taking valacyclovir and seek medical attention right away if you develop a severe or spreading skin rash, blistering, or peeling, or if you notice confusion, unusual drowsiness, or a marked drop in how much you’re urinating. Severe skin reactions, including a reaction called DRESS, which Health Canada added to the Canadian product information in 2022, are uncommon but serious.

Valacyclovir in Pregnancy and Breastfeeding

The data on taking valacyclovir while pregnant or breastfeeding are broadly reassuring but not definitive. A large registry tracking first-trimester exposure to acyclovir (which valacyclovir becomes in the body) found no increase in birth defects, but valacyclovir’s own pregnancy data are more limited. 

In practice, valacyclovir is sometimes used during pregnancy when the benefit clearly outweighs the risk. But that’s a clinical judgment for your doctor, taking your specific situation into account.

Valacyclovir and Alcohol

People often worry about drinking alcohol while taking valacyclovir. The reality is that there’s no known direct interaction between valacyclovir and alcohol — the belief that the two can’t be combined is largely a misconception. 

Alcohol doesn’t stop valacyclovir from working, and valacyclovir doesn’t amplify alcohol’s effects. That said, “no direct interaction” isn’t the same as “drink freely.” 

Alcohol is dehydrating, and since hydration matters for how your kidneys clear this medication, heavy drinking while taking valacyclovir isn’t ideal. Alcohol can also worsen overlapping side effects like nausea or dizziness, and during an active outbreak, your body is better served by rest than by a big night out. 

Valacyclovir in Canada: Cost, Coverage, and How to Get It

Valacyclovir is prescription-only in Canada. 

When filling a prescription, you’ll usually receive a generic version of valacyclovir rather than brand-name Valtrex. Both Valtrex and generic valacyclovir contain the same active ingredient and work the same way.

Can a Pharmacist Prescribe Valacyclovir?

Pharmacist prescribing for minor ailments has expanded across much of Canada in recent years, though exactly which conditions qualify varies by province.

In British Columbia, under the Minor Ailments and Contraception Service, community pharmacists can assess and prescribe for a set list of minor ailments. The two relevant to valacyclovir are cold sores and shingles. Genital herpes isn’t on that list, so a pharmacist can’t start valacyclovir for it.

Please note that pharmacists can only prescribe valacyclovir for uncomplicated cases. If there are frequent or severe recurrences, a question of whether daily suppressive therapy would help, or other co-occurring conditions, the pharmacist may be required to refer you to a physician.

Coverage and Cost

Across Canada, generic valacyclovir is inexpensive and widely covered, while brand-name Valtrex almost always costs more. Because exact prices vary by pharmacy and dispensing fee, it’s best to ask your pharmacist for a current figure.

In BC, generic valacyclovir is a full benefit under PharmaCare’s Low Cost Alternative program, which covers the generic up to a set maximum price. Brand Valtrex is reimbursed only up to that same maximum, so you’d pay the difference unless there’s a documented reason you can’t take a generic.

Is Valacyclovir Right for You?

If you’re dealing with recurrent cold sores, a genital herpes diagnosis, or a shingles outbreak, valacyclovir is a well-established treatment option that can genuinely make outbreaks shorter, milder, and less frequent. It works best when started early, so the sooner you see a doctor, the more effective treatment is likely to be.

If you think valacyclovir might be what you need, you don’t have to wait for an in-person appointment. At Walk-In, Canadian-licensed doctors can assess your symptoms online, advise on a suitable treatment, and send a prescription straight to your pharmacy. Book an online consultation now to get started.

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