Lidocaine plasters for pain after shingles

The UK product information (Versatis) states that the plaster is indicated for the symptomatic relief of neuropathic pain associated with previous herpes zoster infection, known as post-herpetic neuralgia, in adults. This is the long-lasting nerve pain that can follow shingles after the rash has healed.

Lidocaine diffuses continuously from the plaster into the skin, providing a local pain-relieving effect through stabilisation of neuronal membranes, which is thought to reduce sodium channel activity. The hydrogel plaster also has a mechanical action, protecting the hypersensitive area from touch and clothing.

The painful area is covered with the plaster once daily for up to 12 hours within a 24-hour period, and only the number of plasters needed for effective treatment should be used. Each plaster must be worn no longer than 12 hours, and the subsequent plaster-free interval must be at least 12 hours. It can be applied during the day or night.

Apply it immediately after removing it from the sachet and removing the release liner, to intact, dry, non-irritated skin after shingles has healed. Hair in the area must be cut with scissors, not shaved. When needed, plasters may be cut into smaller sizes with scissors before removing the release liner.

It is contraindicated in people with hypersensitivity to lidocaine, other local anaesthetics of the amide type, or any ingredient. The plaster must not be applied to inflamed or injured skin, such as active shingles lesions, atopic dermatitis or wounds, and not to mucous membranes. Avoid eye contact.

Caution is advised in people with severe heart, kidney or liver impairment, and where Class I antiarrhythmic medicines are used, although the amount reaching the bloodstream is low.

The product information is clear that treatment outcome should be re-evaluated after 2 to 4 weeks. If there has been no response after that period, either during wearing time or the plaster-free interval, treatment must be discontinued because potential risks may outweigh the benefits.

Post-herpetic neuralgia is difficult to treat, and the plaster is one option alongside oral medicines such as amitriptyline, gabapentin or pregabalin, chosen by a prescriber depending on other conditions and tolerance.

Application site reactions are very common and are the most commonly reported effects: burning, dermatitis, redness, itching, rash, skin irritation and small blisters. They are localised reactions due to the nature of the product. Uncommon effects include skin lesions and skin injury.

Propylene glycol and parabens in the plaster may cause skin irritation or allergic reactions. If a significant skin reaction develops, remove the plaster and speak to a pharmacist or doctor. The product information notes that a metabolite of lidocaine was genotoxic in rats; the clinical significance is unknown, which is part of why use is limited to what is needed.

Lidocaine crosses the placenta, there are no adequate data from use in pregnant women, and animal studies do not indicate teratogenic potential, so the plaster should not be used during pregnancy unless clearly necessary. Lidocaine is excreted in breast milk, but because it is metabolised fast and almost completely in the liver, only very low levels are expected; there are no studies of the plaster in breastfeeding women, so discuss it with your prescriber.

No effect on the ability to drive or use machinery is expected because systemic absorption is minimal.