Postherpetic neuralgia is a pain that persists in some people who have shingles. It often eases and goes in time. Antidepressant medication can ease the pain in most cases.

What is postherpetic neuralgia?

Postherpetic neuralgia (PHN) is a nerve pain (neuralgia) that persists after a shingles rash has cleared. If the pain goes, but then returns at a later date, this too is called PHN.

Shingles is an infection of a nerve, and causes a typical rash. It is caused by the varicella-zoster virus. About 1 in 5 people have shingles at some time in their life. Shingles can occur at any age, but it is most common in people aged over 50. Most people with shingles have pain, but the pain usually eases soon after the rash clears. PHN is pain that persists.

How common is postherpetic neuralgia?

PHN is unusual in people aged under 50, and if it does occur it tends to be mild. PHN is more likely to develop, and is more likely to be severe, in people aged over 60. About 1 in 4 people aged over 60 who have shingles develop PHN that lasts more than 30 days.

What are the symptoms of postherpetic neuralgia?

PHN causes pain on and around the area of skin that was affected by the shingles rash. Most people with PHN describe their pain as 'mild' or 'moderate'. However, the pain is severe in some cases.

The pain is usually a constant, burning, or gnawing pain. In addition, or instead of this, you may have sharp or stabbing pains that come and go. The affected area of skin is often very sensitive. Even slight touch, such as the rubbing of clothes, or a draught of air on the affected area, may cause pain. You may also have reduced sensation to touch, and itch over the affected area.

Why does the pain persist in some people?

Shingles causes inflammation of the nerve. Pain can be expected whilst the rash and inflammation occur. However, it is not clear why some people continue to have pain when the inflammation has gone. It is thought that some scar tissue in the nerve, or in the nearby part of the spinal cord, may be a factor. This may cause pain messages to be sent to your brain.

Will the pain go away?

Without treatment, PHN typically eases gradually and goes. In about 5 in 10 people with PHN, symptoms are gone by 3 months. However, without treatment, about 3 in 10 people with PHN still have pain after a year.

What are the treatments for postherpetic neuralgia?

General measures
Loose fitting cotton clothes are best to reduce irritating the affected area of skin. Pain may be eased by cooling the affected area with ice cubes (wrapped in a plastic bag), or by having a cool bath. Some people find that putting several layers of 'cling film' over the affected area of skin helps. This allows clothes to slide over the skin without irritating.

Painkillers
Paracetamol, or paracetamol combined with codeine, usually gives some relief. Painkillers are best taken regularly to keep 'on top of the pain' rather than now and then. However, if painkillers do not help then see your doctor about trying an antidepressant medicine.

Antidepressant medicines
An antidepressant medicine in the 'tricyclic' group is a common treatment for PHN. It is not used here to treat depression. Tricyclic antidepressants ease neuralgia (nerve pain) separately to their action on depression. There are several tricyclic antidepressants, but amitriptyline is the one commonly used for nerve pain. Pain is stopped, or greatly eased, in up to 8 in 10 cases of PHN treated with amitriptyline.

A tricyclic antidepressant will usually ease the pain within a few days, but it may take 2-3 weeks. It can take several weeks before you get maximum benefit. Some people give up on their treatment too early. It is best to persevere for at least 4-6 weeks to see how well the antidepressant is working. If an antidepressant works, it is usual to take it for a further 3 months after the pain has gone or eased. After this, the dose is gradually reduced and then stopped. You should re-start the antidepressant quickly if the pain returns.

Tricyclic antidepressants sometimes cause drowsiness. This often eases in time. To try and avoid drowsiness, a low dose is usually started at first, and then built up gradually if needed. A dry mouth is another common side effect. Frequent sips of water may help with a dry mouth.

Anticonvulsant medicines
An anticonvulsant, such as gabapentin or carbamazepine, is an alternative to an antidepressant. This is not to treat convulsions. An anticonvulsant can stop nerve impulses causing pains separate to its action on stopping convulsions. Sometimes an antidepressant and an anticonvulsant are used together.

Other treatments
A variety of other treatments may be tried if the above treatments have not worked. These include various soothing or anaesthetic creams, injections, bio-feedback, transcutaneous nerve stimulation (TENS), ultrasound, and other techniques. These treatments are usually only advised under the supervision of a specialist in a pain clinic.

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