Notes For Patients - By Dr David Bowsher - Shingles Support Society

Information provided by the Shingles Support Society
41 North Road, London N7 9DP - Tel 020 7607 9661

INFORMATION FOR PATIENTS on
SHINGLES AND POST HERPETIC NEURALGIA

By Dr David Bowsher, MA, MD, PhD, FRCPed, FRCPath, co-founder of the Pain Relief
Foundation and consultant neurologist at its Pain Research Institute, Liverpool

If you have shingles - a painful rash on one side of your face or body - you must get in touch with your doctor immediately. Antiviral drugs such as aciclovir, famciclovir or valaciclovir, can help relieve it if they are started within 48 hours of the rash appearing.

If pain persists or comes back after 8 to 12 weeks, then you have post-herpetic neuralgia (PHN). This is far more likely to develop in the elderly than in younger patients after shingles, but no age is totally exempt! Antiviral drugs do not prevent PHN from developing but make it easier to cure if it does occur.

TREATMENT OF PHN

Even the strongest painkillers have little effect on nerve pains (like shingles and PHN). The tried and trusted treatment for PHN consists of two drugs originally developed for the treatment of depression - but no longer used for it, having been replaced by newer drugs. These first-generation "tricyclics" amitrpityline and nortriptyline, have been found to have a specific action on nerve pains. You start with a low dose at bedtime and gradually, over 2 or 3 weeks, build up to a dose of 50 or even 75 milligrams. It doesn't really matter what time of day you take the tablets: one three times a day or all 3 at bedtime (as they make you feel drowsy anyway). Whatever suits you best! It is necessary to build up a concentration of the drug in the body and it may take as long as 4-6 weeks before any effect is felt, though most people will notice helpful effects before then.

Side effects of these drugs are that they can give you a dry mouth, best dealt with by taking sips of water or fruit juice, or by using artificial saliva spray, which is available on prescription. They can also make you feel a bit woozy at first: this usually wears off after a day or two, but this is why we start with a small dose and build it up gradually. If you have side-effects from the drug, drop to the previous highest dose which did not upset you; try increasing again after a week. Eventually, we want you to take the highest dose you can tolerate, up to the limit of the daily amount prescribed by your doctor or the hospital.

Recently, another drug, gabapentin, which was originally developed as an anti-epileptic (anticonvul-sant) drug has also been found to be effective in PHN. It is taken in increasing doses three times a day. It has very few side effects in most people, but may make you drowsy - and if a rash occurs (which is very rare) you must stop taking it. Most doctors prescribe amitriptyline or nortriptyline and gabapentin together for PHN. Other anti-epileptic drugs have not been found to be very effective.

IMPORTANT NOTICES:

Unlike ordinary painkillers, pain is not relieved every time you take a tablet or capsule. The effect of the drugs builds up slowly.
The sooner amitriptyline or nortriptyline are used, the greater the chance of pain being relieved. If treatment for PHN is left for several months or even years, the chance of relief becomes progressively lower; that's why it is so important to go back to your doctor and tell him/her if you have pain two or three months after the original shingles. Indeed it has been found that if a very low dose of amitriptyline is started as soon as the shingles is diagnosed and is taken every night for two or three months, many (but not all) cases of PHN can be prevented. It is not yet know if this is also true for gabapentin.