Anesthetic, Local (Topical)

Local anesthetic is used to numb an area of the body, usually ahead of a surgical procedure.

Overview

Anesthetic for topical application can come in the form of creams, lotions, gels, ointments and sprays. All of these forms of anesthetic work by blocking the sensation of pain in the skin. The drug is applied directly to the area where the pain relief is going to be needed and therefore does not need to travel around the body. The skin acts as a barrier, preventing too much of the active chemicals from being absorbed into the bloodstream.

The localization of the pain relief has several major benefits when compared to the use of a general anesthetic:

  • Surgery can take place whilst the patient is still awake - making it easier to check the patient is OK and reducing the risks associated with unconsciousness
  • Patients do not have to be monitored for as long and so can be discharged much more quickly
  • Local anesthetic can be applied directly to the affected area, so it does not have to interact with the whole of the rest of the body. This makes recovery time much faster.

Administering local anesthetic via topical application does not offer as long-lasting an effect as intravenous injections. It is therefore commonly used for small, non-invasive procedures such as dental procedures which generally take less than half an hour to carry out.

Topical application can be used in conjunction with intravenous local anesthetic to provide additional relief to a patient. It can also help to numb the area before

This is particularly helpful in situations where the local anesthetic will need to be injected into a sensitive area of the body, such as the gums. Patients usually find it more comfortable to have the area numbed using topical application before the injections of local anesthetic are administered.

Local anesthetic can be applied directly to the surface of the eye, and is therefore very useful for ophthalmic procedures such as removing small foreign objects from the eye.

In addition to preparing the body for surgery, local anesthetic can be used in much lower doses in over-the-counter medications. Small quantities of local anesthetic can be used in treatments for mouth ulcers and sore throats to provide localized pain relief. These are available in gels, sprays, ointments and creams and are also applied directly to the area affected.

Conditions treated

  • Pain
  • Preparation for surgery
  • Dental procedures eg. Dental fillings and wisdom tooth removal
  • Eye surgery eg. Cataract removal
  • Sore throats
  • Mouth ulcers
  • Dental fillings
  • Minor skin operations
  • Removal of warts, moles and verrucas
  • Biopsies

Type of medicine

  • Anesthesia

Side Effects

Local anesthetics are widely regarded as being very safe and rarely cause harmful side effects. Unlike intravenous local anesthetic, administering the drug via topical application causes the patient no pain whilst the drug is being applied. Topical application also restricts the amount of the drug which can be absorbed into the bloodstream and therefore usually limits the probability and severity of any side effects. Immediately following application, patients may feel a tingling sensation in the affected area as the nerves begin to be affected.

Topical anesthetic is safe for use for children of all ages, however younger patients may be more likely to experience side effects than adults and weaker doses are usually prescribed.

Topical local anesthetic usually lasts around half an hour, but can take several hours to completely wear off, so patients should be careful in the hours following a procedure involving the drug. Whilst the local anesthetic is still having an effect, patients will not be able to register pain or changes in temperature in the affected area of the body. This is not dangerous in itself, but it can lead to further injury as it may take people longer than usual to recognize that they are hurting themselves. It is therefore not advisable to move around too much until the effects of the anesthetic have worn off.

Occasionally, some patients do experience some temporary side effects after having had a local anesthetic. These can include:

  • Lightheadedness
  • Dizziness
  • Blurred vision
  • Muscle spasms
  • Pins and needles
  • Headaches
  • Muscle weakness
  • Continued numbness
  • Insect bites
  • Minor cuts and scratches
  • Minor burns
  • Allergic reactions
  • Apprehension
  • Difficulty regulating temperature
  • Nervousness
  • Tinnitus
  • Vomiting

These side effects usually occur as the drug is wearing off and will usually vanish completely after the effects of the local anesthetic have dissipated. If patients continue to have these side effects long after full sensation has been restored to the area, they should contact their doctor and seek medical attention.

It is important to remember that if a doctor, dentist or other medical professional is prescribing topical anesthetic for use as part of a procedure or treatment, they will be doing so as they believe the benefits to outweigh the risks. Topical anesthetics are deemed to be extremely safe in most circumstances, but patients should discuss the possibility offside effects and what to look out for with their doctor if they are worried ahead of the treatment.

Allergic reactions to local anesthetic are incredibly rare, but they do happen. Less severe allergic reactions may present as any combination of the following symptoms:

  • Hives
  • Itching
  • Rash/Redness of skin
  • Swelling
  • Stinging

All of the symptoms listed above are associated with an allergic reaction to the drug, and could get worse without treatment. It is important to seek urgent medical attention if you experience any of the symptoms listed above following a local general anesthetic. A very small percentage of patients may develop a more serious allergic reaction to topical local anesthetic. The symptoms of a severe allergic reaction can include:

  • Seizures
  • Fainting
  • Back pain
  • Numbness or tingling in the back or lower legs
  • Difficulty walking
  • Difficulty retaining control of the bladder and/or bowel movements
  • Severe lightheadedness
  • Slow heart rate

If patients experience any of these symptoms at all following a treatment using topical anesthetic, they should go to the emergency room immediately as they could be due to a severe allergic reaction to local anesthetic.

Dosage

Doses of topical local anesthetic prescribed by a doctor will vary depending on the following factors:

  • Age, weight and physical condition of the patient
  • Length of time the anesthetic is required to last
  • The area to which the anesthetic will be applied
  • The condition being treated
  • Whether the patient is currently pregnant
  • Any other medications which the patient is currently taking.

Local anesthetic for topical application will usually come in the form of a spray, gel, ointment, lotion or cream. These medications will normally vary in strength between 1% and 10%.The maximum dose of a particular medication per day and the frequency of application will entirely depend on the strength of the ointment, lotion, spray, gel or cream.

It is possible to overdose on local anesthetic, even when it is applied via topical methods, so it is imperative that patients follow the instructions of the doctor and do not exceed the stated dose.

Interactions

Some drugs cause interactions when used together. These interactions can stop the drugs from working effectively to treat symptoms or can exaggerate, aggravate or cause side effects. Interactions are always a possibility when combining different drugs in treatments, but interactions do not occur for all patients or in all cases. It is always recommended for patients to keep a comprehensive and up-to-date list of all drugs they are taking in order to keep a valid record.

Interactions with local anesthetic are less common when it is combined with topical application as the drug is rarely administered in large enough doses. However, interactions are still possible and caution should always be advised. Some of the drugs which are known to have interactions with topical anesthetics include:

  • Propofol
  • Cordarone
  • Ciprofloxacin
  • Amitriptyline
  • Prozac
  • Zoloft
  • Luvox
  • Diflucan
  • Itraconazole
  • Tamoxifen
  • Carbamazepine
  • Divalproex
  • Phenytoin
  • Valproic Acid
  • Benzodiazepines
  • Xanax
  • Diazepam
  • Propranolol

It is not possible to provide a complete list of all interactions as all circumstances will be unique. Doctors will assess your exact situation and will make a decision as to whether the risk of interactions outweighs the benefits of using a topical anesthetic.

It is not just prescription drugs which can interact with topic anesthetic with potentially harmful consequences. Patients are advised not to drink too much alcohol following treatment with topical anesthetics as this can slow down the body's recovery and potentially aggravate or bring about unwanted side effects. The same is true of marijuana for both medical and recreational use.

It is also possibly for underlying medical conditions or past illnesses to interact with prescription medications. It is especially important to let your doctor know if you are expecting to use local anesthetic and any of the following statements are true:

  • You have ever suffered from liver or kidney disease
  • You are currently taking medication for arrhythmia
  • You are currently breastfeeding
  • You have cuts, sores, bruising or bleeding in or around the area where the drug will be used
  • You have a high fever
  • You currently have an infection or are taking antibiotics
  • You have a history of heart problems
  • You have a history of substance abuse
  • You are currently taking any non-prescribed medication
  • You are taking beta blockers
  • You suffer from high cholesterol

Topical anesthetic is not thought to be harmful to unborn babies, but patients should let their doctor know if they are currently pregnant or trying for a baby.

Warnings

When applied topically, local anesthetic is usually completely harmless. However, when applied excessively to the eye, topic anesthetics can damage the corneal tissue severely and irreversibly. In extreme cases, this has led to patients losing their eye. Doctors are therefore discouraged from prescribing topical anesthetic to treat eye pain at home. There are other drugs, such as anticonvulsants and antidepressants, which are just as effective in reducing the pain and cause little or no damage to the eye itself.

Due to the nature of the medication, it comes in the form of sprays, ointments, gels, lotions and creams. All of these forms of medication can be difficult to measure accurately as it is not a simple case of counting a number of tablets. Caution should therefore be taken by patients treating themselves with medications which contain topical anesthetics.

Patients should not cover areas of the body with band aids, dressings, bandages and shrink wrap after topical anesthetic has been applied. This can cause the body to absorb the drug too quickly and can cause harmful side effects and possibly lead to an overdose. The same is true if the cream, gel, ointment or lotion is applied across a large area as too much of the drug can be absorbed all at once. In some cases, patients who wrapped large areas of their skin after applying topical anesthetic had seizures as a direct result and two patients slipped into a coma and died as a consequence.

Topical anesthetic should never be ingested. Patients should only apply the medication in the manner prescribed by the doctor, dentist, pharmacist or healthcare professional. If ingested, the drug can become much more harmful, as much higher percentage of the active ingredient can be taken into the bloodstream. This is especially true for pets and children, so it is vital that the drugs are kept in a safe place and out of reach.

Storage

Local anesthetic is rarely prescribed for home use so is normally kept under strict conditions in a pharmacy or medical institution. Some forms of the drug need to be kept at temperatures below 25°C. Local anesthetic is commonly present in homes as it appears in small doses in some medications for sore throats and mouth ulcers, it is important to remain vigilant about the storage of these drugs within the home.

As with all medications, topical anesthetic, or medication which includes topical anesthetic as an ingredient, should be kept in its original packaging in a safe place. It should be clearly labelled so that it cannot be confused with other substances or someone else's medication. All drugs should be kept well out of the way of children or pets so that they cannot be ingested accidentally.

Topical anesthetic should not be subjected to extreme changes in temperature, so should be kept somewhere where a consistent room temperature is maintained. Excessive moisture can harm the drug, so it should not be kept in kitchens, bathrooms or other damp environments.

Summary

Topical anesthetic is a form of numbing medication used to provide localized pain relief to specific areas of the body. It is an incredibly useful resource for dentists in particular, as it can provide a short burst of anesthetic relief to reduce the pain felt during dental procedures.

The drug comes in various different forms, which makes it versatile in terms of its possible applications. For this reason, it can be used in a wide variety of different situations by a wide variety of medical professionals. In addition to numbing an area ahead of surgery, topical local anesthetic can prevent patients from experiencing the discomfort associated with local anesthetic injections. The two types of local anesthetic can be combined in order to provide an overall treatment which is more comfortable. Topical anesthetic cream can be applied directly to areas which are more difficult or more painful to access through injections such as the surface of the eyeball or the inside of the mouth.

These drugs are also used as ingredients in over-the-counter medications such as sore throat lozenges and sprays and gels which are used to treat mouth ulcers. These treatments provide an intense burst of localized pain relief which can help patients to continue with their day whilst the injury/condition heals naturally its own time.

Whilst there are a great number of benefits to the use of topical local anesthetic, as with all drugs, there is risk involved. Side effects can be experienced by patients using the drug and although these usually wear off very quickly, they sometimes lead to more serious conditions. Allergic reactions are rare but they can happen and it is possible to overdose if the prescribed dose is exceeded.

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Last Reviewed:
December 24, 2017
Last Updated:
April 02, 2018