Lidocaine belongs to the group of drugs called local anesthetics. Since lidocaine is poorly soluble in water but good in fat, it is suitable for being absorbed through the skin. The agent works in the various layers of the skin and is only absorbed into the bloodstream in small quantities. The transmission capacity of the local nerves, especially the pain-conducting fibers, is blocked and the perception of pain is suppressed. Serious side effects are very rare, but local reactions may occur more frequently.
Read more about the active ingredient: Lidocaine
Duration of action of a lidocaine patch
A lidocaine patch used to treat neuralgia is usually left on the skin for twelve hours and then loses its effect. After removing the patch, there should also be an active substance-free time of twelve hours before the next patch is applied. When used briefly to prepare for an injection, the effect lasts only a few minutes to hours.
There are mainly two large groups of areas of application for lidocaine patches.
- The first area is post-therapeutic neuralgia. After herpes zoster infections, nerve pain occurs in around 10 to 20 percent of those affected. The pain occurs in spite of the healed skin and the lidocaine patch may only be used on intact skin. Risk factors for post-therapeutic neuralgia are: Herpes zoster infections of the face, the female gender, old age, tumor diseases and a lack of primary antiviral therapy against zoster
Please also read: Shingles or herpes zoster
- The second area of application is the prevention of pain in small interventions. In paediatrics in particular, the affected children are given a lidocaine plaster on their hands before an access is made to prevent the pain from puncturing. Other small surgical treatments of the skin can also be performed under local anesthesia with lidocaine patches.
Since the effect only lasts for a short time, long-term therapy for chronic pain does not make sense. In the case of back pain and similar illnesses, the plasters often do not work sufficiently, as the active ingredient hardly penetrates deeper than into the layers of the skin.
Lidocaine patch for back pain
When it comes to back pain, there are various causes for the symptoms. In most cases, lidocaine patches are insufficient for muscle-related pain or spinal discomfort because the active ingredient does not penetrate deep enough. For back pain in the skin area or pain that can be traced back to the nerves in the subcutaneous tissue, a lidocaine patch can soothe the pain. After herpes zoster infections in the back area, the pain of post-therapeutic neuralgia can also be reduced there.
The trigeminal nerve is the fifth cranial nerve that emerges from the brain stem and divides into three main branches. These branches protrude from the skull at certain points on the face. The points are above the eyes, next to the nose and on the chin. Trigeminal neuralgia is a very painful irritation of the nerve with facial pain. Sodium channel blockers, which include lidocaine, can be used for acute therapy. However, if the improvement is insufficient, risky operations must be considered. However, the active ingredient can also be administered via other forms of administration such as creams and ointments.
Read our article on this: Trigeminal neuralgia or lidocaine ointment and lidocaine cream
Side effects that affect the whole body are very rare and actually only known in the case of a significant overdose. In this case, allergic reactions and circulatory problems can occur. Local reactions, which include reddening of the skin, swelling, burning and itching, are more common.
Interactions with other drugs are rather rare, but can occur with CYP3A4 inhibitors and antiarrhythmics. In the event of side effects, a doctor should be consulted to discuss further treatment.
Allergic reactions to lidocaine patches
Local allergic reactions to lidocaine patches occur regularly. Those affected report itching, reddening of the skin and burning sensation in the area of the patch. It should be noted, however, that there may be an allergic reaction to the adhesive in the plaster.
Systemic allergies up to allergic shock are rare, but can occur especially if the dose is too high. An allergic shock can lead to swelling and irritation of many mucous membranes and thus also to swelling in the area of the airways.
For more detailed information on this topic, also read: anaphylactic shock
Effect of lidocaine patches
Lidocaine is a poorly water-soluble but fat-soluble agent and can therefore be easily absorbed through the skin. The lidocaine migrates to the nerves, which are located in the subcutaneous tissue, and accumulates in the cell membrane. Normally, the cell membrane is permeable to sodium and other electrolytes through various channels. The concentration of the electrolytes creates an action potential which is passed on to the brain. The sensations and pain are consciously perceived in the brain. Lidocaine blocks the sodium channels in the cell membrane and prevents the development of an action potential. The transmission of pain to the brain is prevented.
Since nerve fibers have different thicknesses and sheaths for different sensations, with a suitable dosage only the sensation of pain is switched off and only with a higher dose also the sensation of temperature and pressure. Lidocaine is gradually broken down and removed from the membrane, so the effect is not long-lasting. In the plasters it only penetrates through the upper layers of the skin and does not work deeply. Due to the low absorption in the bloodstream, a central effect on other parts of the body is not possible.
Are there lidocaine patches available without a prescription?
Lidocaine does not require a prescription and can be bought independently. However, there is a pharmacy obligation, as the pharmacist is able to explain the side effects and the handling. If you are unsure whether the lidocaine patches are suitable for your own complaints, you should consult a doctor who may then write down alternatives.
Cost of lidocaine patch
- Patches for preparation for injections, with the trade name Emla®, can be bought on the Internet for around € 15 for two patches.
- Versatis® patches, for the treatment of neuralgia, cost € 95 for 20 patches. If the neuralgia is diagnosed by a doctor, the health insurance company bears these costs.