Medical Health Encyclopedia

Possible side effects and complications of all nucleoside analogues include:

• Rash.
• Headache.
• Fatigue.
• Tremor.
• Nausea and vomiting.
• Seizures (very rarely).
• Complications of intravenous administration, which is used for AIDS and other immunocompromised patients, include an increased risk for kidney damage and blood clots at the injection site.

As with antibiotics, physicians are concerned about signs of increasing viral resistance to acyclovir and similar drugs, particularly in immunocompromised patients (such as those with AIDS).

Brivudin. Brivudin (Helpin, Zostex) is another anti-viral agent of note that only needs to be taken once a day and is proving to be as effective as the standard agents. It is not yet available in the US. Studies suggest that it as at least as effective as the standard agents. It is also only needs to be taken once a day, which improves compliance.

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Foscarnet. Foscarnet (Foscavir) is a powerful antiviral agent known as a pyrophosphate analogue. It is used in cases of VZV strains that have become resistant to acyclovir and similar drugs. Administered intravenously, the drug can have toxic effects; it can impair kidney function (which is reversible) and cause seizures. Fever, nausea, and vomiting are common side effects. It can also cause ulcers on genital organs. As with other drugs, it does not cure shingles.

Oral Corticosteroids

Oral corticosteroids, including prednisolone or prednisone, are powerful anti-inflammatory medications. They have some benefit for reducing pain and accelerating healing in acute attacks when used with acyclovir. (They are not recommended without acyclovir.) They also may be helpful for improving symptoms of Bell's palsy and Ramsay Hunt syndrome. Corticosteroids do not appear prevent a further attack or reduce the risk for PHN. Side effects of corticosteroids can be severe and oral steroids should be taken at as low a dose and for as short a time as possible. (Injected or intravenous steroids, however, may offer specific relief for PHN without significant side effects.)

Epidural Blocks

Epidural blocks are injections of local anesthetics or steroids outside the tough membrane surrounding the spinal cord (the dura matter). The injected substances block the nerves and offer relief from acute herpes zoster pain for some people. Some studies, but not all, have indicated that if they are administered early enough (within two months), they may prevent nerve damage that leads to postherpetic neuralgia. Combinations of anesthetics with steroids in the epidural blockade may be particularly beneficial. This procedure is invasive, however, and is not widely used.