Medically reviewed by Jessica Swirble, PharmD
Last updated on 5/2/2024

Drug Information | Side Effects | Use & Dosage | Request a Prescription

The use of acyclovir can lead to various side effects in some individuals.

Common mild side effects of acyclovir use include:

• Headache
  
• Dizziness or lightheadedness
  
• Nausea or upset stomach
  
• Diarrhea
  
• Fatigue
  
• Tiredness
  
• Skin rash
  
• Sensitive skin that may burn more easily in the sun
  
• Vision changes
  
  

More severe side effects of acyclovir use can include:

• Rapid heartbeat
  
• Severe allergic reactions (such as rash, itching, swelling of the face, tongue, or throat, trouble breathing)
  
• Changes in urine volume
  
• Blood in the urine
  
• Extreme tiredness
  
• Easy bruising or bleeding
  
• New signs of infection (like a sore throat that doesn't go away, fever)
  
• Jaundice (yellowing of the skin or eyes)
  
• Seizures
  
• Loss of consciousness
  
• Hallucinations
  
• Confusion
  
  

If you experience any severe or concerning side effects while taking acyclovir, contact your healthcare provider right away.

What should I tell my healthcare provider before using acyclovir?
Tell your healthcare provider about any existing medical conditions, allergies, or other medications you are taking before starting treatment with acyclovir. This includes prescription drugs, over-the-counter medications, and dietary supplements, as they may interact with acyclovir.

Tell your provider if you are taking these medications or supplements:

• Medications that affect kidney function
  
• Antibiotics
  
• Other antiviral drugs
  
• Immunomodulators
  
• Tizanidine
  
• Nonsteroidal anti-inflammatory medications (NSAIDs)
  
  

You should also mention medical conditions such as:

• Kidney disease
  
• Liver disease
  
• A weakened immune system (from HIV, bone marrow transplant, kidney transplant)
  
• Neurological disorders
  
• Seizure disorder
  
• Hematologic disorders (problems with red blood cells, white blood cells, platelets, etc)
  
  

If you are pregnant, planning to become pregnant, or breastfeeding, consult your healthcare provider before using acyclovir to assess potential risks and benefits.

Take acyclovir exactly as prescribed by your healthcare provider. Do not exceed the recommended dose or duration of treatment.

Acyclovir should be taken with or without food based on your healthcare provider's advice. It is important to follow their instructions for optimal effectiveness.

Stay hydrated while taking acyclovir, especially if you are taking higher doses, to help prevent kidney issues.

In case of an acyclovir overdose, seek medical attention immediately. Symptoms of overdose may include agitation, loss of consciousness, and seizures. If you suspect an overdose, contact the poison control helpline at 1-800-222-1222 or call emergency services.