Acyclovir (Apotex): Uses, Side Effects and Dosage

ABOUT THIS MEDICATION

What the medication is used for and what it does:

ACYCLOVIR is an antiviral medicine.

Treatment of Shingles (Herpes Zoster)

ACYCLOVIR is used to treat shingles (herpes zoster) infections. Shingles is caused by the varicella-zoster virus. The virus multiplies in and eventually destroys affected skin cells. ACYCLOVIR stops the virus from multiplying and therefore from spreading to neighbouring healthy cells. It cannot replace a cell which has been damaged by the multiplying virus, but it will facilitate the process of healing.

Treatment and Suppression of Genital Herpes

ACYCLOVIR is used to treat initial episodes of genital herpes.

Genital herpes is a sexually transmitted infection caused by the herpes simplex virus (HSV). HSV causes small, fluid-filled blisters in the genital area which break down into ulcers/sores which may be itchy or painful. The fluid in these blisters contains the virus which causes the disease. It is a feature of all herpes viruses that once in the body, they stay there throughout life alternating between active (outbreak) and inactive states.

When taken on a daily basis, ACYCLOVIR can also be used to prevent the HSV infection from coming back. This type of treatment is called suppressive therapy.

When it should not be used:

You should not use ACYCLOVIR if you are allergic to or react badly to acyclovir or valacyclovir or any other components of the formulation of ACYCLOVIR (see "What the non-medicinal ingredients are" section). Tell your doctor if you have ever had an allergic reaction to any of these ingredients.

What the medicinal ingredient is:

ACYCLOVIR tablets contain the active ingredient acyclovir.

What the important non-medicinal ingredients are:

ACYCLOVIR 200 mg Tablets contain the non-medicinal ingredients colloidal silicon dioxide, croscarmellose sodium, lactose monohydrate, magnesium stearate and microcrystalline cellulose.

ACYCLOVIR 400 mg Tablets contain the non-medicinal ingredients colloidal silicon dioxide, croscarmellose sodium, magnesium stearate, micro-crystalline cellulose and the colouring agent red ferric oxide.

ACYCLOVIR 800 mg Tablets contain the non-medicinal ingredients colloidal silicon dioxide, croscar-mellose sodium, magnesium stearate, microcrystalline cellulose and the colouring agent Brilliant Blue FCF Lake 12%.

What dosage forms it comes in:

ACYCLOVIR is available in tablets containing

200 mg, 400 mg or 800 mg of acyclovir.

WARNINGS AND PRECAUTIONS

Before using ACYCLOVIR , tell your doctor if:

• You have kidney problems or if you are 65 years of age or older. Your doctor may give you a lower dose of ACYCLOVIR and/or ask you to stay hydrated.
• You are severely immunocompromised (e.g. suffering a severe disease or have recently undergone an organ transplant, and are taking immunosuppressant drugs for either of these conditions).

• You are pregnant, planning to become pregnant, breastfeeding or planning to breastfeed.

The safety and effectiveness in children less than 2 years of age are not known.

You must make sure you drink plenty of liquids such as water while you are being given ACYCLOVIR.

Feeling drowsy or sleepy may impair your ability to concentrate and react. Make sure you are not affected before you drive or operate machinery.

When using ACYCLOVIR for suppression of genital herpes, your doctor may periodically stop your drug therapy in order to reassess your need for continuous treatment. The effect of long-term use in humans has not been fully assessed. Prudence is therefore suggested when choosing continuous, long term therapy with ACYCLOVIR. Suppression of recurrent genital herpes is therefore, only recommended in those who are severely affected. Some patients experience increased severity of the first episode of genital herpes after stopping treatment.

Genital herpes is passed from one person to another through direct intimate contact. To reduce the risk of transmission, wash your hands immediately if you touch your skin sores, and do not touch other parts of your body until you have done so. Especially avoid intimate contact with others when the disease is visible. Herpes virus particles may also be released when you do not have blisters or sores. For this reason, it is safest to believe that you can spread the infection to your partner even when sores are not present.

Although decreased sperm counts were observed in animals treated with high doses, these effects did not occur in humans.

PROPER USE OF THIS MEDICATION

Medication should not be shared with others. The prescribed dosage should not be exceeded.

Tablets should be swallowed whole, with water.

Usual dose for shingles:

For the treatment of shingles (herpes zoster), the usual dose of ACYCLOVIR is 800 mg every 4 hours, 5 times daily for 7 to 10 days. ACYCLOVIR must be taken as early as possible within 72 hours of the onset of lesions.

Usual dose for genital herpes:

For the treatment of an initial episode of genital herpes, the usual dose of ACYCLOVIR is 200 mg every 4 hours, 5 times daily (maximum 1 g daily) for 10 days. ACYCLOVIR must be taken as early as possible following onset of signs and symptoms.

For the suppression of genital herpes, the usual dose of ACYCLOVIR is 200 mg 3 to 5 times daily or 400 mg twice daily. You should follow dosing instructions carefully. The objective is to keep enough of the drug in the body at all times to prevent the herpes virus from multiplying. Your doctor will try to prescribe the minimum dose required to do this in your case and may therefore increase or decrease your dose during the first few weeks. Follow your doctor's instruction carefully to ensure that you get the best possible response to treatment.

For the treatment of recurrent episodes of genital herpes, the usual dose of ACYCLOVIR is 200 mg every 4 hours 5 times daily for 5 days. ACYCLOVIR must be taken at the earliest sign or symptom (prodrome) of recurrence.

Overdose:

If you think you have taken too much ACYCLOVIR, contact your healthcare professional, hospital emergency department or regional Poison Control Centre immediately, even if there are no symptoms.

Missed dose:

If you forget to take a dose, take it as soon as you remember. Then continue with the next dose at the proper time interval. Do not double doses.

SIDE EFFECTS AND WHAT TO DO ABOUT THEM

As with any widely prescribed medication, adverse events in association with the use of ACYCLOVIR are reported from time to time.

Common side effects may affect up to 1 in 10 people:

• Headache,
• Nausea, diarrhea, upset stomach vomiting
• Feeling unwell
• Weakness, lack of energy
• Skin tingling, itching

Other side effects include: dizziness; high temperature (fever);itchy, bumpy rash; skin reaction after exposure to light (photosensitivity); hair loss; unusual bruising or bleeding; shortness of breath; effects on blood and urine tests; swelling of the face, lips, mouth, tongue or throat; increases in the enzymes that work in the liver; feeling agitated or confused; feeling shaky, unsteady and a lack of co-ordination; difficulty speaking or hoarseness; seeing or hearing things that are not really there; feeling drowsy or sleepy; inability to think or judge clearly or concentrate; disturbances of behaviour, speech and eye movements; unconsciousness; yellowing of the skin and whites of the eyes, inflammation of the liver; and changes to blood test results (reduced numbers of red blood cells, white blood cells, or blood platelets).

HOW TO STORE IT

Store ACYCLOVIR tablets at room temperature (20° to 25°C). ACYCLOVIR tablets should be stored in a dry place and protected from light.

Keep your ACYCLOVIR tablets in a safe place. Keep out of reach and sight of children.

REPORTING SIDE EFFECTS

You can report any suspected side effects associated with the use of health products to the Health Canada by:

• Visiting the Web page on Adverse Reaction Reporting (https://www.canada.ca/en/health-canada/services/drugs-health-products/medeffect-canada/adverse-reaction-reporting.html) for information on how to report online, by mail or by fax; or
• Calling toll-free at 1-866-234-2345.

NOTE: Contact your health professional if you need information about how to manage your side effects. The Canada Vigilance Program does not provide medical advice.

MORE INFORMATION

If you want more information about ACYCLOVIR:

• Talk to your healthcare professional
• Find the full product monograph that is prepared for healthcare professionals and includes this Consumer Information by visiting the Health Canada website (https://health-products.canada.ca/dpd-bdpp/index-eng.jsp). Find the Consumer Information on the manufacturer’s website (http://www.apotex.ca/products), or by calling 1-800-667-4708.

Last Revised: MAY 29, 2026