Vasovagal Syncope

as it affects people on The Spectrum

"The Spectrum" generally means the autism Spectrum, including Asperger's syndrome, HFA, PDD, Kanner's autism, and other autism spectrum conditions. Many of us are comfortable with the generic reference of "autistic".

What This Is

Vasovagal syncope incident to needles or syringes (also vasovagal reflex, vaso vagal reflex syncope or vasovagal asystole) is a form of fainting, specific to needles. Generally it is a reaction to IV (intravenous insertion of a needle).
Vasovagal syncope also refers to fainting unrelated to needles, for example incident to a cardiovascular condition or other pathology. This article does not address synscope resulting from those causes.
Syncope is fainting (or perhaps a type of fainting). The vasovagal reflex is a reflex reaction to either needles or invasive penetration of a vein. Hence, vasovagal syncope is a fainting reaction to intravenous penetration or the like.

This generally requires a needle phobia and a strong vasovagal reaction.

Vasovagal syncope is relevant to autism because sensitivities to physical contact and reactions to such sensitivies are commonly observed among people with autism. As of the time of this writing, this was based on ancedotial descriptions of the association of vasovagal syncope with autism.

Vasovagal syncope can more generally be used to describe an inappropriate reflex in the nervous system which leads to opening (dilation) of the blood vessels along with slowing of the heart rate (bradycardia). This article focuses specifically on vasovagal syncope as related to needle phobia or IV phobia.

While related to needle phobia, the actual mechanism is a physical response to a physical stimulus. Therefore, phobia desensitization will not necessarily resolve the issue.

An Experience

My own experience was that the fainting part was sort of cool (but not something I'd want to repeat because of the risk, etc.)

I have a phobia for IV, probably relating to early childhood surgery. Until 2005, this resulted in pre-syncope reactions, without full syncope. I went in for a blood test in '05 at the Lankenau Hospital, in Wynnewood, PA.

I had just finished having my blood drawn and was asked to sit in the waiting room for a few minutes until I was ready to go.

"Uh, is it okay if I stay here for a minute?"


This was followed by my passing out. There were two nurses in attendance and they were trying to revive me. I was cognizant of most of what was going on, and was aware of ammonia smell. At the time, I remembered seeing two ammonia sticks taped beneath the chair's armrest, and was cognizant enough during the syncope to figure that the ammonia sticks were being used.

The ammonia had no effect, but it is possible that both interpretation of these activities during syncope and the ineffectiveness of the ammonia were the result of my neurological type.

One of the nurses was asking me to come to. My sense of time was perhaps a bit compressed, considering the events I recalled after the event.

After I came to, the nurses explained what happened. I proceeded past the Lankenau Hospital's retail pharmacy (appropriately named "The Main Line Pharmacy") and was able to safely drive off to get a nice breakfast.


Vasovagal syncope is not considered to be a risk factor for critical activities. For example, the FAA's (US aviation agency) medical standards require a review for "A disturbance of consciousness without satisfactory medical explanation of the cause". Vasovagal syncope by definition is a satisfactory medical explanation (and with no suggestion of relevant recurrence).

Medical Procedures

Since a vasovagal reaction can injure or even kill a patient, having on hand an oxygen source and a "crash cart" for cardiac resuscitation is mandatory with any needle-phobic patient undergoing a needle procedure.

A patient subject to vasovagal reaction should be given TAC ointment or the equivalent to avoid an vasovagal syncope incident.

Topical mixtures of tetracaine, adrenalin, and cocaine (TAC ointment) or tetracaine, adrenalin, and lidocaine. All these mixtures must be applied for 1 to 2 hours and have a depth of anesthesia of only 2 to 3 mm.


If you have a needle or IV phobia, you should memorize the name "vasovagal syncope" and the medical procedures above (or at least "TAC").

In the event you are asked to provide a blood sample, insist on this being performed at a hospital or similar medical facility because of the vasovagal syncope condition.

You are at risk if you have an IV phobia. You should consider yourself to be subject to vasovagal syncope if you have experienced reduced blood pressure (other than that caused by actual giving of blood) during intravenous procedures.

Vasovagal synscope can occur on penetration or withdrawal of the needle. If your stress (or symptoms of shock) occurs during withdrawal, you should inform the physician because the physician may not be aware of that issue.

For most people, these precautions are not necessary for an ordinary jab (intermuscular injection).

Implied Consent

"Implied Consent" is a part of most drunk driving laws under which a person is deemed to "consent" to a search without a warrent while driving. Typically a separate offense of refusal to consent is applied in lieu of the drunk driving charge, but the state must prove drunk driving without test results.

This applies to blood test requests. Some (or most) jurisdictions consider blood tests to be so offensive as to not be required (e.g., California). Other jurisdictions use blood tests when other types of testing are unavailable. Pennsylvania may be the only US state that has allowed blood testing to be requested by the state under the implied consent law despite "fear of needles".

As of 5-07, there was no reported US case law identifying vasovagal synscope in connection with implied consent.

It is likely that the reason there are no reported cases is that no prosecutor has been idiotic enough to bring such a case to appeal. (It is impossible to Nyfong a defendant on a losing case!) Since vasovagal synscope has a small but definite risk of fatality associated with it (cardiac arrest and brain death), the courts would have to address that issue. This goes beyond "being afraid of needles".

As a practical matter, a person who is subject to vasovagal synscope should state that xe is "unable" and specify vasovagal synscope. It may be possible to delay the refusal until the blood test is imminent because police have been known to use blood tests as a threat.

If one is brought to a hospital, one can refuse after requesting information about the fatality risks. (You'll either get a straight answer or inadequate answers.) As to the delay in testing, the state would have the choice of proving impairment by retrograde extrapolation or by simply using a different test.

None of this is a "get out of jail free" card for drunk driving. Normal drunk driving prosecution uses breath testing. (Urine testing is also possible but apparently not common.)

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First posted 03-Jul-06. Last revised 08 May 10.

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