Post-herpetic neuralgia is a persistent nerve pain that occurs at the site of a previous attack of a condition called shingles.
It's estimated that up to one in every five people with shingles will go on to develop post-herpetic neuralgia, and older people are particularly at risk.
The pain can improve after a few months and medication can help control it in the meantime, although some cases are more persistent and can even be permanent.
Why does it happen?
In post-herpetic neuralgia, the varicella zoster virus (the virus that causes chickenpox and shingles) damages nerves under the skin of the affected area.
It is not clear why some people with shingles develop post-herpetic neuralgia, but increasing age, pain in the early (prodromal) stage of a shingles attack and severe pain throughout an episode of shingles are all associated with an increased risk of the condition.
Signs and symptoms
The main symptom of post-herpetic neuralgia is continuous nerve pain in an area previously affected by shingles. The pain has been described as burning, stabbing, shooting, aching or throbbing.
The affected area may also:
feel intensely itchy
be more sensitive to pain than usual (hyperalgesia)
feel painful as a result of something that would not normally hurt (allodynia), such as a light touch or a cool breeze
Living with post-herpetic neuralgia can be very difficult, as it can interfere with your ability to carry out certain daily activities, such as dressing and bathing, and can lead to further problems such as extreme tiredness (fatigue), sleeping difficulties and depression.
Seeing your GP
It is important to revisit your GP if you experience persistent pain after having shingles to discuss the medications available to help control it.
Post-herpetic neuralgia is easy to diagnose based on your symptoms and medical history because it only occurs as a complication of shingles, and the pain will be in the area of the body that was affected by the condition.
How post-herpetic neuralgia is treated
Many people with post-herpetic neuralgia make a full recovery within a year of developing the condition. But occasionally the nerves do not heal completely and symptoms last for several years or permanently.
Medication can ease the symptoms of post-herpetic neuralgia, although they may not relieve the pain completely.
As post-herpetic neuralgia generally doesn't respond to standard painkillers such as paracetamol and ibuprofen, alternative medications will need to be prescribed.
These will often be medications originally intended to treat depression(antidepressants) or epilepsy (anticonvulsants), but have since been found to also be effective in relieving nerve pain.
Can post-herpetic neuralgia be prevented?
There is no definite way to prevent post-herpetic neuralgia. However, antiviral medication will often be given early during an episode of shingles to help reduce the risk of complications such as post-herpetic neuralgia.
Alternatively, you can reduce your risk of post-herpetic neuralgia by having the shingles vaccination to try to prevent an attack of shingles occurring.
This vaccine is routinely offered to older people. It is given as a single injection to anyone aged 70. There is also a catch-up programme for those aged 79 and, from September 2014, 78 and 79-year-olds. You will only need to have this vaccine once.
If you wish to have the shingles vaccine and you are not eligible vaccination programme, you will usually need to visit a private clinic. Private vaccination is likely to cost £100 to £200.
Treating post-herpetic neuralgia
The pain associated with post-herpetic neuralgia can often be reduced with medication, although some simple self-help measures can also be useful.
If you have post-herpetic neuralgia, you can try a number of things that may help reduce the painful symptoms of the condition.
Some measures you can take to reduce pain are described below.
wear comfortable clothing – clothes that are too tight or made of rough or synthetic material may irritate your skin and make your symptoms worse; wearing cotton or silk clothing will usually cause less irritation
cover sensitive areas – you may find some areas of your skin are more affected by post-herpetic neuralgia than others; if your clothes tend to rub in certain areas, try covering them with a plastic wound dressing or cling film
use cold packs –unless your post-herpetic neuralgia is made worse by cold, you could try using gel-filled cold packs to numb the pain: simply place the pack in the freezer to cool it down before placing it gently against your skin
If your pain is severe, you are likely to need medication prescribed by your GP to help control it.
These medications may not necessarily completely eliminate the pain, but they can help reduce it. They are also not all suitable or effective for everyone, so you may need to try a number of different medications to find the one – or combination – that works best for you.
The nerve pain associated with post-herpetic neuralgia doesn't usually respond to standard painkillers, although your GP may sometimes suggest using paracetamol or a combination of paracetamol and codeine initially to see if it has an effect.
If these are not effective, alternative medications may be needed. These will often be medications originally intended to treat depression(antidepressants) or epilepsy (anticonvulsants), but have since been found to be effective in relieving nerve pain because they "damp down" nerve impulses.
While you are using these medications, your progress will be regularly reviewed to assess how effectively they are working and whether you are experiencing any side effects.
Depending on the outcome of your reviews, your medication may be changed or the dosage may be altered. If the medications your GP can prescribe do not help, you may need to be referred to a pain specialist for further treatment.
Some of the main medications used to treat post-herpetic neuralgia are outlined below.
Amitriptyline and duloxetine are the two main antidepressants that can be prescribed by your GP to treat post-herpetic neuralgia.
Doses of these medications will usually start low and build up over a few weeks, depending on the benefits and side effects. It may take a few weeks to feel the full effects.
Common side effects of these medications include dry mouth,constipation, dizziness and drowsiness. Because of the dizziness and drowsiness that can be caused by these medications, you may be advised not to drive until you are on a stable dose that does not cause this side effect.
If these medications are still not effective in controlling your pain after you have been taking them for several weeks, or they are causing significant side effects, your dose will need to be gradually reduced over one week or more to prevent withdrawal effects.
Gabapentin and pregabalin are the two main anticonvulsants that can be prescribed by your GP to treat post-herpetic neuralgia.
Like the antidepressants mentioned above, these should be started at a low dose, with the dose gradually increased over a few days or weeks. They also usually need to be taken for a few weeks until they start to take effect.
Common side effects of gabapentin and pregabalin include dizziness, drowsiness, poor memory, increased appetite and weight gain. Do not drive or operate heavy machinery if you experience dizziness or drowsiness after taking these medications.
If they are still not effective in controlling your pain after you have been taking them for several weeks, or they are causing significant side effects, the dose of these medications will need to be gradually reduced over one week or more.
In some cases, pain-relieving medication that is applied directly to the painful area (topical treatments) may be suitable.
There are two main types of topical treatment used for post-herpetic neuralgia – capsaicin cream and lidocaine plasters.
Capsaicin is the substance that makes chilli peppers hot and is thought to work in nerve pain by stopping the nerves sending pain messages to the brain.
A pea-sized amount of capsaicin cream is rubbed on the painful area of skin three or four times a day.
Side effects of capsaicin cream can include skin irritation and a burning sensation in the treated area when you first start treatment.
Do not use capsaicin cream on broken or inflamed skin and always wash your hands after applying it.
This is a large sticking plaster that contains a local anaesthetic. It may be useful when pain affects only a small area of skin.
It is stuck over the area of painful skin and the local anaesthetic is absorbed into the skin that is covered.
If the medications prescribed by your GP are not effective in managing your pain, you may be referred to a specialist pain clinic to help manage your pain.
While you are waiting to be referred to a pain clinic, you may be prescribed a medication called tramadol. This belongs to a group of medicines called opioids. It is an effective painkiller that can help reduce neuropathic pain.
Common side effects of tramadol can include feeling sick, vomiting, dizziness and constipation. Like all opioids, tramadol can also be addictive if taken over long periods of time, so it should be prescribed for the shortest time possible.
Specialists in a pain clinic may recommend taking other, stronger, types of opioids such as morphine or oxycodone if the medications listed above have not helped. These will initially be prescribed by your specialist, although your GP can continue to prescribe them thereafter.