Complications of shingles are more likely if you have a weakened immune system (the body's natural defence system) or are elderly.
Some of the main complications associated with shingles are described below.
Postherpetic neuralgia is the most common complication of shingles. It's not clear exactly how many people are affected, but some estimates suggest as many as one in five people over 50 could develop postherpetic neuralgia as the result of shingles.
Postherpetic neuralgia can cause severe nerve pain (neuralgia) and intense itching that persists after the rash and any other symptoms of shingles have gone.
Types of pain experienced by people with postherpetic neuralgia include:
- constant or intermittent burning, aching, throbbing, stabbing, or shooting pain
- allodynia – where you feel pain from something that should not be painful, such as changes in temperature or the wind
- hyperalgesia – where you are very sensitive to pain
Postherpetic neuralgia sometimes resolves after around three to six months, although it can last for years and some cases can be permanent. It can be treated with a number of different painkilling medicines.
Read about treating postherpetic neuralgia.
If one of your eyes is affected by shingles (ophthalmic shingles), there's a risk you could develop further problems in the affected eye, such as:
- sores (ulceration) and permanent scarring of the surface of your eye (cornea)
- inflammation of the eye and optic nerve, the nerve that transmits signals from the eye to the brain
- glaucoma – where pressure builds up inside the eye
If not treated promptly, there's a risk that ophthalmic shingles could cause a degree of permanent vision loss.
Ramsay Hunt syndrome
Ramsay Hunt syndrome is a complication that can occur if shingles affects certain nerves in your head.
In the US Ramsay Hunt syndrome is estimated to affect 5 in 100,000 people every year, and may affect a similar number of people in the UK.
Ramsay Hunt syndrome can cause:
- hearing loss
- the sensation that you or the environment around you is moving or spinning (vertigo)
- hearing sounds coming from inside your body, rather than an outside source (tinnitus)
- a rash around the ear
- loss of taste
- weakness (paralysis) of your face
Ramsay Hunt syndrome is usually treated with antiviral medication and corticosteroids.
The earlier treatment is started, the better the outcome. Around three-quarters of people given antiviral medication within 72 hours of the start of their symptoms usually make a complete recovery.
If treatment is delayed, only about half of those treated will recover completely.
Those who don't make a full recovery may be left with permanent problems, such as a degree of permanent facial paralysis or hearing loss.
A number of other possible problems can also sometimes develop as a result of shingles, including:
- the rash becoming infected with bacteria – see your GP if you develop a high temperature, as this could be a sign of a bacterial infection
- white patches (a loss of pigment) or scarring in the area of the rash
- inflammation of the lungs (pneumonia), liver (hepatitis), brain (encephalitis), spinal cord (transverse myelitis), or protective membranes that surround the brain and spinal cord (meningitis) – these complications are rare, however
Shingles is rarely life threatening, but complications like those mentioned above mean around 1 in every 1,000 cases in adults over the age of 70 is fatal.