The best numbing cream for cosmetic and dermatology procedures is a compounded topical with several anesthetic ingredients. A compounding pharmacy can make a topical anesthetic that includes multiple anesthetics in one formulation. A common formulation is one that contains benzocaine, lidocaine, and tetracaine, also referred to as a BLT cream. This formulation can be made in different strengths and is custom made with every order.
Compounded Topical Anesthetic Ingredients
Some topical anesthetics have been in use for at least a hundred years. Topical anesthetics are proven to be safe and effective when used appropriately. The two common types are amide and ester anesthetics. A compounded topical anesthetic usually contains a combination of three anesthetic ingredients: benzocaine, lidocaine, and tetracaine. This is why the formulation is called BLT cream.
Benzocaine – An ester local anesthetic that is frequently used to numb teeth, gums, oral ulcers, and sore throat and also to numb prior to a surgical procedure. It may also be used in the treatment of ear pain. It is made in the form of lozenges, gels, throat sprays, creams, and solutions. For oral use in dentistry, typically a 20% product can be found from dental suppliers.
Lidocaine – An amino amide anesthetic that is one of the most commonly used local anesthetics in dentistry (as an injection). Lidocaine is also an effective topical anesthetic. It is sometimes used with epinephrine. Lidocaine is a different type of anesthetic than benzocaine and tetracaine. In cases where a patient is allergic to ester anesthetics, they often can instead use lidocaine. It is generally accepted that fewer patients are likely to be allergic to lidocaine than to other topical anesthetics (although allergies to anesthetics are rare).
Tetracaine – Another ester anesthetic (like benzocaine), tetracaine is also used to numb the mouth, throat, and ears. It is also used to numb the eyes and in emergency departments to provide immediate numbing after an injury.
Benefits of Compounded Topical Anesthetics
For many dermatological procedures a compounded topical anesthetic can be the sole anesthetic used. In some situations where an injected local anesthetic would be used, a compounded topical can be used as a replacement. Many patients have a fear of needles and in addition, an injection can distort the face in a way that makes a cosmetic procedure difficult to perform accurately. Injections typically cause edema (swelling) at the injection site which can affect the treatment. Needle phobia is also a reason why patients may avoid visiting a dermatologist for a cosmetic treatment. Topical anesthetic both numbs the patient physically and also provides a psychological benefit in easing anxiety prior to a procedure.
Each anesthetic has different characteristics – they have varying times until onset of action, last different lengths of time, and have different side effect profiles. Lidocaine is typically faster acting and longer lasting than other topical anesthetics. However an anesthetic like tetracaine actually diffuses more slowly – it is more lipophilic than lidocaine and concentrates in the stratum corneum. This prolongs the anesthetic effect at the application site while minimizing systemic uptake. The combination of anesthetics provides both a rapid onset and a durable duration of action.
The benefits of a combination of topical anesthetics have been well established in clinical trials. In a clinical trial of 60 patients given a combination of lidocaine and tetracaine vs a placebo, the percentage of patients who experienced inadequate pain relief was measured. Only 9% of patients who received the LT combination reported inadequate pain relief (they still felt some pain) while this was true of 66% of patients in the placebo group. Researchers found that 75% of the patients who received the LT cream did not experience pain.
Numerous other clinical trials have been conducted on anesthetic combinations, sometimes with creams but also often with patches. Topical anesthetics are not just used prior to procedures but also to reduce chronic pain.
Safety Considerations and Contraindications
Self-Application – The main cause of adverse effects related to compounded topical anesthetics has been self-application by patients at home. These topical anesthetics are much more powerful than OTC topical anesthetics that patients may be used to purchasing. Using on a large area of skin, like prior to hair removal on an entire leg, can quickly lead to toxic effects. Patients may use inappropriate techniques like occlusion on large surface areas of the skin, leaving the cream on too long, and applying too much. There are standardized charts of average body surface area that may be helpful in determining a patient’s body surface area and the appropriate amount of anesthetic to use based on toxicity levels of an anesthetic. These are things a patient will not be considering if they are applying a topical at home.
Individual Physiology – A patient’s individual physiology can greatly affect how a topical works and its potential adverse effects. Not every patient will experience the same rate of absorption and the same anesthetic effects. While the effects should not vary widely, some patients may not get as numb as other patients or may experience side effects more easily. This is why it is often good to conduct a test on a small area of skin before applying to a larger area.
Broken or Inflamed Skin – Topical anesthetics should not be applied to broken or inflamed skin. This can lead to high systemic levels of anesthetic very rapidly, potentially causing adverse effects.
Methemoglobinemia – Methemoglobinemia is a condition where the oxygen levels in the blood are diminished. One of the characteristic symptoms of this condition is blue-colored skin. Other symptoms include dizziness, headache, nausea, and difficulty breathing. It can be diagnosed based on these symptoms and a low level of oxygen in the blood. It can be caused by different drugs including benzocaine. While extremely rare, it is a risk and the risk is more significant in pediatric patients. In European countries, the contraindication for benzocaine applies to pediatric patients under 12 years of age. The condition is most common in patients under 2 years of age.
Benzocaine, Lidocaine, Tetracaine Cream
The cream should be applied with an applicator or a gloved hand to prevent exposure to the anesthetic by the provider. Some providers will occlude the area after applying topical anesthetic. However with compounded topical anesthetics this is generally not recommended as it can lead to increased systemic uptake.
The anesthetic effects of a compounded topical anesthetic will quickly be apparent. BLT cream will usually work within 15-20 minutes with maximum effectiveness at 30 minutes. The cream should be wiped off completely at this point. This should be followed by thorough cleansing of the skin.
BLT cream can only be obtained through the services of a compounding pharmacy. The formulation can be adjusted based on the provider’s directions. To learn more about compounding BLT you can reach out to National Pharmacy directly.
Articles
Topical local anesthesia: focus on lidocaine–tetracaine combination – Local and Regional Anesthesia
Topical Anesthetics for Dermatologic Procedures: A Review Article – American Society for Dermatologic Surgery