What happens if you are allergic to the anesthesia drugs you receive? 

This is one of the most common questions my colleagues and I are asked. 

Allergy denotes a response by the body's immune system to a `foreign` substance. Usually the substance (or `allergen`) is something not ordinarily harmful to the body, such as penicillin. 

Severe allergic reactions during anesthesia are fortunately rare, occurring only once in every 5,000 to 25,000 anesthetics. Unfortunately, these reactions can sometimes be fatal; about a 3% (3 in 100) mortality has been documented. 

The most severe form of allergic reaction is known as anaphylaxis. During an anaphylactic reaction the patient may experience difficulty breathing, as air passages close up. Swelling of the face and mouth can occur, and a reddish skin rash is also sometimes seen. The heart and blood vessels are severely affected, and this is the hallmark of the condition: the heart rate increases and blood pressure can drop to dangerously low levels. 

Anaphylaxis during general (asleep) anesthesia presents in a similar way but there are three unique features. 

First, the patient who is asleep cannot tell us about light-headedness or breathlessness which might be early warning symptoms. 

Second, during a typical general anesthetic, many drugs are given, and it is hardly ever clear which of these drugs have caused the reaction. 

Third, during anesthesia there are many other potential causes for the blood pressure to drop or the air passages to close off. A diagnosis of anaphylaxis is therefore not always easy to establish. 

Although severe allergic reactions may be a little more difficult to detect under anesthesia, a patient having an anaphylactic reaction under anesthesia is actually in a very good place to get promptly treated. All the necessary equipment and medication to successfully treat the reaction is at hand in the operating room. Anesthesiologists are experts in the treatment of such reactions. Treatment may include insertion of a breathing tube, administration of intravenous fluids, and a variety of drugs, the most important of which is epinephrine (adrenaline). Early and appropriate treatment is almost always successful. 

It is worth noting that drugs are not the only cause of allergic reactions. For example, one important non-drug cause of anaphylaxis is allergy to natural rubber (`latex`). Reactions to latex are a special problem during anesthesia as surgical gloves are usually made of this material. 

Two final notes about allergy. First, many allergic reactions are not life-threatening, resulting only in a transient skin rash or such symptoms as nausea and vomiting. Secondly, many drug reactions are not true allergies, representing only an increased sensitivity to common side-effects of the medication. 

Is there a maximum dose recommendation for versed? 

Not that I'm aware of. Versed, like most other anesthetic agents, is titrated to effect. In other words, you give some, as you assess the effect clinically and with monitoring equipment. Then you give some more if necessary. 

What is the name of a common anesthesia drug often administered along with Versed? Propinol? Proplyn? Propol? 

The drug you are thinking of is called propofol, originally introduced into the US by the company Zeneca, and marketed as Diprivan. Versed is one of the trade names for midazolam. 

I am taking MS-Contin under a doctors care for chronic pain. Does this medicine interfere with novacain used in a dentist's office for a filling? If so what does a dentist use to numb the patients mouth? 

ﾠMS-Contin is a long-acting form of morphine, taken by mouth, which is often used for chronic pain conditions. 

Novocain is the trade name for the local anesthetic procaine. Procaine was one of the first local anesthetics developed, and the trade name has become synonymous with local anesthetics in general. 

Novocain, and other commonly used local anesthetics do not interfere with morphine. Pain killers may of course help to dull any dental pain that occurs after the dentist is done. You are unlikely to have a problem relating to your use of MS-Contin at the dentist`s office.