Ask the Doctors: Even after rash, pain of shingles may linger
Dear Doctor: I’m a 78-year-old woman who developed shingles in December 2014. The rash settled in the nerves on my left side, from under the breast, to the waist and around the middle of my back. Is there anything I can take to ease the pain? Would the vaccine help?
Dear Reader: Shingles is a reactivation of the herpes zoster virus — the virus that causes chickenpox. When people contract chickenpox, usually as children, the virus makes its way along their sensory nerves, ending up at the nerve cells along the spine. The virus then sits within the cells in a dormant state. It can stay there for the rest of a person’s life and not cause problems, with the body’s immune system keeping the virus in a dormant state.
However, when immunity decreases, the virus can replicate within a nerve cell, following a particular nerve pathway to the skin and creating a rash along that pathway. The most common risk factor for developing shingles is age, with 80- to 89-year-olds having 10 times greater risk compared with those 10 years old and younger.
The nerve pain created by shingles can be very severe and can persist even after all the lesions have disappeared. The pain can be burning, sharp or stabbing and can worsen with even the lightest touch. When the pain lasts for more than four months, the diagnosis is termed “postherpetic neuralgia.” That’s the pain syndrome you have.
There are many medications for postherpetic neuralgia. Tricyclic antidepressants like amitriptyline, nortriptyline and desipramine work to decrease pain signals from the skin to the central nervous system. However, they’re often not well-tolerated in older patients and can lead to sedation, dry mouth and worsening memory. They would not be my first choice for you.
Gabapentin (Neurontin) and pregabalin (Lyrica) work directly through the nerves to decrease pain. Gabapentin causes much more drowsiness compared to pregabalin, so many of my patients who have difficulty sleeping at night due to the pain of postherpetic neuralgia do well with it. However, because people with symptoms that also occur during the day often can’t tolerate the sedating effects of gabapentin, I switch many of these patients to pregabalin; although this drug can cause drowsiness, it is better tolerated. The anti-seizure drug valproic acid also can significantly decrease pain.
Capsaicin, the active component of chili peppers, is known for irritating the sensory nerves, but perhaps remarkably, can lead to pain relief when used in cream form for those with postherpetic neuralgia. Note that you must apply capsaicin multiple times per day, and for many people, the burning, stinging sensation is intolerable.
Opiates also can relieve the acute pain, but when used long-term, they can cause tolerance and addiction.
As for the vaccine, although you had shingles more than two years ago, it could still reduce the risk of future episodes. However, no vaccination studies have been done in patients who have already had shingles, so the potential benefit is unclear. In addition, the vaccine won’t reduce your current nerve pain.
In summary, I recommend speaking to your doctor about medications like gabapentin or pregabalin and whether to get the shingles vaccine to perhaps decrease the risk of future episodes.