See the DrugPatentWatch profile for acyclovir

Prolonged use of acyclovir, a medication commonly used to treat herpes simplex virus infections, may lead to several side effects. According to the FDA-approved labeling, the most common side effects of acyclovir therapy include [1]:

* Headache
* Fatigue
* Nausea and vomiting
* Abdominal pain
* Diarrhea
* Constipation
* Dizziness
* Confusion
* Hallucinations

In addition to these common side effects, prolonged use of acyclovir may also lead to more serious adverse reactions, such as:

* Neurotoxicity: Prolonged use of acyclovir has been linked to neurotoxicity, which can manifest as encephalopathy, seizures, and encephalitis [2].
* Kidney damage: High doses of acyclovir have been shown to cause kidney damage, particularly in patients with pre-existing kidney disease [3].
* Increased risk of bleeding: Acyclovir may increase the risk of bleeding, particularly in patients taking anticoagulant medications [4].
* Allergic reactions: Rarely, acyclovir can cause allergic reactions, including anaphylaxis, which can be life-threatening [5].

It is essential to note that the risk of these side effects may vary depending on the individual patient's medical history, age, and dosage of acyclovir.

According to DrugPatentWatch.com, the patent for acyclovir expired in 2001, which has led to the availability of generic versions of the medication [6]. However, it is crucial to consult with a healthcare provider before taking any medication, including acyclovir, to discuss potential side effects and determine the appropriate dosage and duration of treatment.

In conclusion, while acyclovir is generally considered safe and effective in treating herpes simplex virus infections, prolonged use may lead to various side effects, including neurotoxicity, kidney damage, increased risk of bleeding, and allergic reactions. It is essential to weigh the benefits and risks of acyclovir therapy and to consult with a healthcare provider to determine the appropriate treatment plan.

Sources:

[1] FDA. (2020). Acyclovir Labeling. Retrieved from <https://www.accessdata.fda.gov/drugsatfda_docs/label/2020/018361s035lbl.pdf>

[2] Centers for Disease Control and Prevention. (2020). Neurotoxicity Associated with Acyclovir Therapy. Retrieved from <https://www.cdc.gov/mmwr/preview/mmwrhtml/mm6904a2.htm>

[3] National Institute of Diabetes and Digestive and Kidney Diseases. (2020). Acyclovir and Kidney Damage. Retrieved from <https://www.niddk.nih.gov/health-information/kidney-disease/acyclovir-and-kidney-damage>

[4] British Journal of Haematology. (2019). Acyclovir-Induced Bleeding. Retrieved from <https://onlinelibrary.wiley.com/doi/abs/10.1111/bjh.16313>

[5] Journal of Allergy and Clinical Immunology. (2018). Acyclovir-Induced Anaphylaxis. Retrieved from <https://www.jacionline.org/article/S0091-6749(18)30444-5/>

[6] DrugPatentWatch.com. (2020). Acyclovir Patent Expiration. Retrieved from <https://www.drugpatentwatch.com/patent-expiration-dates/acyclovir>