What is Herpes Zoster
The rash of herpes zoster is a manifestation of re-activated varicella zoster virus that impacts almost one million patients per year. It is characterized by a painful unilateral vesicular eruption within a specific dermatome.
By definition, herpes zoster does not cross the midline. It additionally is accompanied by significant lancinating, burning neuritis and neuralgia that can bedebilitating. Given its’ prevalence, this disease is seen across a wide variety of settings, including primary care, urgent care, and the emergency department.
The scope of this article will focus on the acute and chronic management of both acute herpes zoster as well as the management of post herpetic neuralgia.
Antiviral Medications for Herpes Zoster
The two most important aspects of management of acute herpes zoster include both antiviral therapy as well as pain management. Antiviral therapy is particularly important given its’ significant impact in reducing the rate of post herpetic neuralgia.
Given the viral nature, duration of symptoms plays a key role in whether anti-viral therapy should be initiated. The goal of anti-viral therapy is to promote quicker healing, decreasing the severity and duration of symptoms, preventing new lesions from forming, and decreasing viral shedding. The goal of decreasing viral shedding is to decrease transmissibility. Additionally, the overall goal is to reduce progression to post-herpetic neuralgia.
The general recommendation is that if symptoms have not been present longer than 72 hours in duration, anti-viral therapy should be initiated. If the patient is presenting with greater than 72 hours of symptoms, the clinician should use judgement and shared decision making to determine if anti-viral therapy will be indicated. If lesions are still developing, anti-virals may still have a clinical benefit.
An additional benefit to using anti-viral therapy is that it is generally a low risk intervention. Anti-virals for herpes zoster are generally well tolerated, but rarely can cause nausea, headache, or diarrhea. Kidney function should also be taken into account when prescribing anti-viral medicine.
The three main anti-virals include valacyclovir, famciclovir, and acyclovir. The doses are as follows: valacyclovir is 1000 MG three times per day for 7 days. Famciclovir is 500 MG three times per day for 7 days. Acyclovir is 800 MG 5 times per day for 7 days.
Although acyclovir has been the most studied and is deemed safest in pregnancy, the five times a day dosing makes compliance difficult. Famciclovir was associated with a decreased duration of post herpetic neuralgia symptoms.
Controlling the Pain in Herpes Zoster
An additionally important goal of management includes pain control. Patients with the rash of herpes zoster may have mild to moderate or even severe pain. The management of mild pain includes alternating NSAIDs and acetaminophen. For moderate pain non-responsive to initial conservative therapy, a short course of codeine or tramadol may be indicated.
For severe pain, patients may benefit from oxycodone, hydrocodone or other narcotic medicine. As always, the patient’s entire clinical history and psychosocial history should be taken into account.
Additional recommendations have been controversial in the past. According to most sources, there is no indication for tri-cyclic antidepressants or anti-convulsants in the acute setting. One practice that many clinicians follow is the use of oral glucocorticoids. Further studies have demonstrated no benefit in terms of pain control, quality of life, or end outcome with the use of steroids in acute herpes zoster treatment.
Unfortunately, many patients may continue to have symptoms of neuralgia long after their rash has cleared. The neuritis can continue for many months or even years after first diagnosis.
Acute herpes zoster generally is defined as less than 30 days in duration. Subacute zoster lasts less than 4 months. Post herpetic neuralgia is defined as continued pain in the area of previous rash for greater than four months from onset. Risk factors thought to contribute to the development of PHN include increased age, greater levels of pain, and greater skin involvement of the initial rash.
The first line treatment for post herpetic neuralgia is a tricyclic antidepressant, particularly amitriptyline or nortriptyline. TCAs should be avoided in patients with glaucoma, heart disease, or epilepsy. Additionally, due to their anticholinergic effects, should be used very cautiously in the elderly. Dry mouth and constipation are common side effects.
Another particularly helpful option is an anticonvulsant, including gabapentin or pregabalin. These may be more reasonable options for patients who have one of the above comorbidities or were not able to tolerate a tricyclic antidepressant. A third line option for post-herpetic neuralgia are opioids, but given their side effect profile and potential for abuse, are usually avoided.
Additional options for pain management include topical pain creams. Capsaicin ointment has been used with mixed results. Topical lidocaine can be beneficial if the patient has comorbidities and cannot tolerate the above oral therapy. Lidocaine patches can be worn for up to 12 hours and may offer pain relief for patients.
Pharmacies may be able to do compounding of the above ingredients to provide a safer alternative that is not systemically absorbed. Tylenol and ibuprofen may be used routinely, but should be avoided if the patient has significant liver, gastrointestinal, or kidney disease.
Herpes zoster remains a very common dermatologic condition that is encountered across various clinical settings. Early initiation of anti-viral medicine may reduce the rate of progression to post-herpetic neuralgia.
Adequate pain management remains paramount to patient quality of life. Post herpetic neuralgia remains an unfortunate, but treatable complication.