Lidocaine is a medication classified as a local anesthetic. It functions by temporarily blocking nerve signals in the affected area, which can help to numb pain and reduce itching.
Understanding Lidocaine for Itching
Lidocaine can be used to alleviate itching associated with various conditions. One area of research suggests its potential in managing atopic dermatitis, a chronic inflammatory skin condition characterized by intense itching and skin lesions. Studies indicate that lidocaine may alleviate these symptoms by targeting specific sensory neurons involved in the itch response.
Specifically, the charged molecule QX-314, which is a derivative of lidocaine, has shown similar effects in animal models of atopic dermatitis. This molecule can enter certain ion channels and selectively inhibit a subpopulation of sensory neurons. Furthermore, genetic silencing of sensory neurons that express NaV 1.8 has been found to reduce skin inflammation and itch in these models, highlighting the role of these neurons in the condition.
It's important to note that while blocking TRPV1-positive nociceptors (pain-sensing neurons) can reduce persistent itch, it does not affect skin inflammation in the atopic dermatitis model. This suggests a distinction between how sensory neurons modulate skin inflammation and itch. Consequently, NaV 1.8+ sensory neurons appear to play a significant role in the pathogenesis of atopic dermatitis, positioning lidocaine as a potential anti-inflammatory and anti-pruritic agent for this condition.
How to Use Lidocaine Transdermal and Topical Systems
When using lidocaine transdermal products or topical systems, it is crucial to follow the directions provided on your prescription label carefully. If any part of the instructions is unclear, do not hesitate to ask your doctor or pharmacist for clarification.
General Application Instructions:
- Always apply a new lidocaine patch or topical system after removing the previous one.
- Avoid allowing lidocaine transdermal to come into contact with your eyes.
- Wash your hands thoroughly after handling lidocaine patches or topical systems.
Specific Instructions for Lidocaine 1.8% Topical System:
- You may apply the 1.8% topical system after moderate heat exposure, such as 15 minutes of heating pad use on a medium setting.
- If using the prescription version, you can shower for up to 10 minutes or be immersed in water for up to 15 minutes.
- If the topical system becomes wet, gently pat the affected skin dry. Do not rub the skin or the system itself.
Managing Dislodged or Lifted Patches/Systems:
- If the topical system comes off completely or lifts at the edges, reattach it by pressing firmly on the affected areas.
- If the system comes off completely more than once and fails to adhere, remove it and apply a new one. Do not exceed a total of 12 hours of use with a single system.
When to Consult a Doctor
If you are using nonprescription lidocaine 4% patches, contact your doctor if:
- Your pain lasts for longer than 7 days.
- Your pain initially improves but then worsens.
Important Precautions and Potential Interactions
Allergies and Sensitivities:
Before using lidocaine transdermal, inform your doctor and pharmacist if you have any allergies to lidocaine or other similar medications, such as benzocaine, bupivacaine, etidocaine, mepivacaine, prilocaine, procaine, or tetracaine. It is also important to mention any allergies to other medications or ingredients in the lidocaine transdermal product. Your pharmacist can provide a list of these ingredients.
Medication Interactions:
Always inform your doctor and pharmacist about all the medications you are currently taking or plan to take, including prescription and nonprescription drugs, vitamins, nutritional supplements, and herbal products. This information helps your doctor adjust dosages or monitor you for potential side effects. A specific nonprescription product that may interact with lidocaine transdermal is acetaminophen (Tylenol). Ensure your doctor and pharmacist are aware if you are taking these medications before starting lidocaine transdermal.
Pre-existing Conditions:
Inform your doctor if you have any pre-existing conditions, particularly heart, lung, or liver disease.
Pregnancy and Breast-feeding:
If you are pregnant, planning to become pregnant, or are currently breast-feeding, discuss this with your doctor before using lidocaine transdermal. If you become pregnant while using lidocaine patches or topical systems, contact your doctor immediately.
Surgery:
If you are scheduled for any surgery, including dental surgery, inform the doctor or dentist that you are using lidocaine patches or topical systems.
Missed Doses
Lidocaine is typically used as needed. However, if your doctor has instructed you to use lidocaine patches or topical systems regularly:
- Apply the missed dose as soon as you remember.
- If it is almost time for your next scheduled dose, skip the missed dose and resume your regular dosing schedule.
- Do not apply a double dose to compensate for a missed one.
Potential Side Effects
Lidocaine patches or topical systems may cause side effects. If any of the following symptoms occur, remove the patch or topical system and discontinue use until the symptoms subside:
- Burning or discomfort at the application site
- Redness or swelling of the skin under the patch
Serious Side Effects:
Seek immediate medical attention if you experience any of the following serious side effects:
- Hives
- Rash
- Blisters
- Bruising
- Difficulty breathing or swallowing
- Swelling of the face, throat, tongue, lips, eyes, hands, feet, ankles, or lower legs
- Hoarseness
- Fast pulse or breathing
- Unusual thirst
- Nausea
- Vomiting
- Confusion
- Weakness
- Dizziness
- Fainting
- Pale, gray, or blue-colored skin
- Headache
- Shortness of breath
- Lightheadedness
- Fatigue
Other Potential Side Effects:
Lidocaine transdermal may also cause other side effects, including:
- Lightheadedness
- Nervousness
- Inappropriate happiness
- Confusion
- Dizziness
- Drowsiness
- Ringing in the ears
- Blurred or double vision
- Vomiting
- Feeling hot, cold, or numb
- Twitching or shaking that you cannot control
- Seizures
- Loss of consciousness
- Slow heartbeat
Storage and Disposal
Store lidocaine products at room temperature, away from excessive heat and moisture. Do not store them in the bathroom. Keep patches and topical systems inside their sealed envelopes until ready for use. Fold used patches or topical systems so that the adhesive side sticks to itself. Safely discard them in the trash, ensuring they are out of reach of children and pets.
Keep all medications out of sight and reach of children. Always lock safety caps and store medications in a secure location that is out of their sight and reach. Do not flush this medication down the toilet. Instead, utilize a medicine take-back program. Consult your pharmacist about available take-back programs in your community.
Important Reminders
Keep all scheduled appointments with your doctor. Do not allow anyone else to use your medication. If you have questions about refilling your prescription, consult your pharmacist. Maintain a written list of all prescription and nonprescription medications, vitamins, minerals, and dietary supplements you are taking. Bring this list with you during doctor's visits or hospital admissions.