From the Guidelines
Acyclovir and Thrombocytopenia
Acyclovir does not commonly cause thrombocytopenia, but it may be associated with this condition in rare instances, particularly at high doses or with prolonged treatment 1.
- The risk of thrombocytopenia is not well established, but it is more likely to occur with high-dose intravenous acyclovir.
- Monitoring of renal function is recommended for patients receiving high-dose IV acyclovir, but laboratory monitoring for thrombocytopenia is not typically needed unless the patient has substantial renal impairment 1.
- It is essential to note that thrombotic thrombocytopenic purpura/hemolytic uremic syndrome has been reported in HIV-infected patients treated with high-dose valacyclovir, but not at doses used for therapy of HSV infection 1.
- In general, acyclovir is considered safe, and nausea or headache are more common side effects than thrombocytopenia 1.
From the FDA Drug Label
The following hematologic abnormalities occurred at a frequency of less than 1%: anemia, neutropenia, thrombocytopenia, thrombocytosis, leukocytosis, and neutrophilia. Hematologic and Lymphatic: Disseminated intravascular coagulation, hemolysis, leukocytoclastic vasculitis, leukopenia, lymphadenopathy. Thrombotic thrombocytopenic purpura/hemolytic uremic syndrome (TTP/HUS), which has resulted in death, has occurred in immunocompromised patients receiving acyclovir therapy.
Yes, acyclovir can cause thrombocytopenia as it is listed as one of the hematologic abnormalities that occurred at a frequency of less than 1% in clinical trials 2. Additionally, thrombotic thrombocytopenic purpura/hemolytic uremic syndrome (TTP/HUS), a condition that includes thrombocytopenia, has been reported in immunocompromised patients receiving acyclovir therapy 2. Key points:
- Thrombocytopenia occurred in less than 1% of patients in clinical trials
- TTP/HUS, which includes thrombocytopenia, has been reported in immunocompromised patients 2, 2
From the Research
Acyclovir and Thrombocytopenia
- Acyclovir has been reported to cause thrombocytopenia in several case studies, although it is considered a rare side effect 3, 4, 5, 6.
- The exact mechanism of acyclovir-induced thrombocytopenia is not fully understood, but it is thought to be related to the formation of antibodies that target platelets 3, 4.
- The onset of thrombocytopenia typically occurs within days to weeks after starting acyclovir therapy, and resolution of the condition usually occurs after discontinuation of the drug 3, 4, 5, 6.
- Patients with certain underlying conditions, such as systemic lupus erythematosus (SLE), may be at increased risk of developing acyclovir-induced thrombocytopenia 6.
- Regular monitoring of platelet counts is recommended for patients taking acyclovir, especially those with underlying conditions that may increase the risk of thrombocytopenia 6.
Case Reports
- A 72-year-old female patient developed immune thrombocytopenia after taking acyclovir for herpes zoster, with a temporal relationship between the start of acyclovir and the onset of thrombocytopenia 3.
- A 67-year-old male patient developed severe thrombocytopenia with tongue hematomas as the first sign after taking acyclovir for varicella zoster virus (VZV) infection 4.
- A 58-year-old male patient with acquired immune deficiency syndrome (AIDS) developed severe thrombocytopenia after starting acyclovir therapy 5.
- A patient with SLE developed thrombocytopenia within days of starting acyclovir therapy, which resolved after discontinuation of the drug and treatment with intravenous immunoglobulin 6.
Comparison with Other Drugs
- Entecavir, another antiviral drug, has also been reported to cause thrombocytopenia, highlighting the importance of recognizing drug-induced thrombocytopenia as a reversible cause of thrombocytopenia 7. However, this is not directly relevant to the question of whether acyclovir causes thrombocytopenia.