Can You Be Allergic To Dental Anesthesia?

Dental anesthesia allows your dentist to do a wide variety of procedures with a complete lack of pain for you. While it’s possible to be allergic to dental anesthetics, this is very rare.

In any event, dental professionals are trained how to handle this situation if it ever does happen. This article will discuss that in more detail a bit later.

Many people take modern dental anesthesia for granted. Dentistry is an ancient art, dating back many thousands of years. However, pain-free dentistry wasn’t an option until about the middle of the nineteenth century.

In 1844, a dentist named Horace Wells first demonstrated the use of nitrous oxide in dental patients. By the beginning of the Civil War, ether and chloroform were in use for both surgery and dentistry, but it wasn’t until 1904 that Novocaine, the first local anesthetic, was discovered. The concept of local anesthesia was born.

What are the Different Types of Anesthetics Used by Dentists?

Dentists typically use several types of anesthesia, depending on the procedure:

  • Inhalant
  • Local
  • Topical
  • Intravenous sedation


The inhalant nitrous oxide is commonly used in many dental procedures, especially for very anxious patients. It’s mixed with oxygen and breathed into the lungs through a small mask. The gas works to both dull pain sensations and create a feeling of well-being.

All anxiety seems to melt away. You will be somewhat aware of your surroundings, but it won’t bother you as the dentist works. Because the gas also tends to release inhibitions, it’s sometimes called laughing gas.

Nitrous oxide is very short-acting and must be breathed in at close intervals to maintain the effect. Once the mask is removed, you will recover quickly from any effects.


Local anesthetics are injected into the mouth to numb a certain area. These drugs work to block pain signals from being transmitted to the brain. Dentists know exactly which nerve areas need to be blocked for any particular procedure. Some common local dental anesthetics are:

  • Bupivacaine
  • Novocaine
  • Articaine with epinephrine
  • Marcaine
  • Carbocaine

Epinephrine, also called adrenalin, is included with certain local anesthetics to reduce blood flow to the area. This effect both increases the power of the local agent and reduces the amount of local anesthetic required.


Topical dental anesthetics may be in the form of gel, spray, liquid or patch. They typically contain benzocaine or lidocaine and produce a numbing sensation in the local area. The numbing effect penetrates the gum tissue to a depth of about three-quarters of an inch.

This is enough to help reduce the pain of the initial local anesthetic injection. Both benzocaine and lidocaine have a low allergic response profile, but either can produce a local allergic response at the application site. These reactions are rare.

IV Sedation

Intravenous sedation is another form of treatment your dentist may use to keep you comfortable during certain procedures. Intravenous sedation isn’t technically an anesthetic in itself, but rather a supplement to it.

It involves the administration of drugs in the tranquilizer class, such as diazepam, midazolam and lorazepam. These produce a calm, drowsy state that eliminates anxiety and tends to have an amnesiac effect. This means that you will likely remember very little of the procedure itself. Intravenous sedation is very useful for patients with dental phobias.

Allergic Reactions

These reactions are rare and typically limited to a mild response. Before your dentist treats you for the first time, he or she will question you about any food or drug allergies that you already know about. Be sure to answer these questions completely and honestly.

If you’ve had an allergic response to a dental anesthetic in the past, it is likely to happen again. In the case of a known drug allergy, your dentist will select another anesthetic agent that is safe for you.

Inhalant Reactions

Nitrous oxide is a short-acting drug. After your procedure, your dentist may give you oxygen to breathe, which helps to clear the gas from your system faster. While nitrous oxide may make you feel dizzy and disoriented, these effects generally wear off very quickly in a matter of minutes.

True allergy to this substance is another matter. It’s unlikely, but symptoms could include:

  • Hives
  • Wheezing
  • Chills
  • Rising body temperature

Local and Topical Anesthetic Reactions

True allergic reactions to the types of local anesthetics used in modern dentistry are exceedingly rare. Possible symptoms could include a localized sensation of itching, localized swelling and possibly a rash or redness around the affected area.

Breathing difficulties are always a potential threat in any kind of allergy, drug-related or not. This can occur with food allergies and insect stings, too.

A reaction to a topical dental anesthetic would be likely to produce a localized reaction similar to that of an injected local anesthetic one, but possibly milder, since less of the substance is applied to the area.

Reactions to Intravenous Sedation

Reactions to this will depend on the drug agent used. While it’s certainly possible for anyone to be allergic to any drug, these reactions are also rare. The symptoms of an allergy to an intravenous sedation drug would likely be similar to that of other dental anesthetic reactions. This could include itching, hives, swelling of the local area or the airway and redness at the injection site.

Treatment of Dental Anesthetic Reactions

A mild reaction may need no treatment. It will subside on its own, but a drug called diphenhydramine may be given to reduce symptoms by blocking a chemical called histamine in the body. Histamine causes allergic symptoms like itching and hives. In more severe reactions, epinephrine may be given.

Antihistamine Information

NameGeneric NameAdult
Makes You
BenadrylDiphenhydramine25-50 mg
4-6 hours
AllegraFexofenadine60 mg
once or twice
(most people)
ClaritinLoratadine10 mg
once daily
(most people)
Many brandsClemastine1.34 mg

This will help to relax blood vessels around the airway and restore breathing to normal. You may receive oxygen as well. Although rare, lidocaine can cause heart rhythm complications. If this happens, you may receive medications to reverse this effect.

The major goals of allergic treatment are to remove the allergen, if possible, treat symptoms as they appear and give supportive care until the body recovers on its own. Once you’ve had an allergic reaction, it’s important to avoid exposure to that substance in the future. The next reaction could be far worse.

What to do if you Know You’re Allergic to a Dental Anesthetic

Always let your dentist know about any prior issues with any kind of anesthetic, dental or not. There are always safe alternatives. An allergy will not prevent you from getting the treatment you need, so don’t worry about that.

Your dentist is highly trained in the chemistry and effects of anesthetics. If one causes a problem, another may not. It’s always possible that the allergy is to something else in the anesthetic preparation, such as a preservative.

In that case, another product not containing that preservative will likely be suitable for you. Your dentist will know exactly what to do to choose a safe option for your situation.


Keep in mind that allergic reactions to dental anesthetics occur less than 1% of the time. Your dentist is trained to recognize and treat any symptoms of dental anesthetic allergies. It’s important to always tell your dentist about any medical conditions you may have.

Some of them, such as diabetes or a seizure disorder, may make a possible reaction more likely in general, even if it’s not allergic in nature. If you’re pregnant, be sure to let your dentist know. X-rays and certain medications may not be administered to you at this time.

After the administration of any kind of dental anesthetic, staff will be watching you closely for any signs of a problem. You may not be aware of this observation, but patient safety is always paramount to your dentist at all times.

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