Ask the Pharmacist

Q) I recently fainted and, after what seemed like a battery of tests, my doctor shrugged and said she believes it was just a vasovagal response. What on earth does that mean?

A) Vasovagal responses are extremely common nervous feedback type phenomena that all of us are capable of experiencing to lesser or greater degrees. Before we go into the characteristics of this response, let’s take a quick anatomical detour and look at the source of it all.

The Vagus nerve is the 10th cranial nerve and one of the most important in our body. It originates in our brain stem, works its way down our face (connecting to our eyes, throat, ears & tongue) before heading downwards where it interacts with every major organ in our body. No wonder it is called the Vagus since that word means “wanderer”.  No other nerve in our body has such broad and far reaching effects as the Vagus.

Within the brain, it helps regulate anxiety and mood. In the gut, it increases acid secretion, the movement of food throughout and the production of digestive enzymes. And this list really just goes on and on; within the pancreas, it helps to regulate our blood sugars, in the kidneys it is involved with water balance and sodium excretion, in the liver it helps with bile production and detoxification and in the sex organs it plays a role in both fertility and sexual pleasure.

Finally, in the heart, which is where its role in the vasovagal response comes into play, it controls both the heart rate and our blood pressure. This response is automatic, meaning that once it kicks in, there is little we can do about it. It occurs as a result of stimulation of the vagus nerve which then sets off a chain of events resulting in a wide variety of unpleasant sensations which are frightening but also relatively harmless.

Initially, the heart rate slows and the blood vessels within the legs widen (dilate) which causes the blood to “pool” within the legs resulting in a sudden drop of blood pressure throughout the body. This drop in blood pressure means less blood is reaching the brain which trigger certain sensations or, at its worst, result in a brief loss of consciousness, a condition known as vasovagal syncope.

Having this happen to you, to repeat, does not mean there is anything wrong with you. We all have the potential to have this reflex, we just vary from each other in how easy it is to trigger and the degree to which we react.

Common triggers include both internal and external ones such as; emotional stress, the sight of blood or blood being drawn such as during a medical test, fear, heat, standing for a long period of time, trauma, standing up too quickly, having a bowel movement, pain or when suffering from a gastrointestinal illness.

Symptoms beyond fainting include blurred or so-called tunnel vision, dizziness, a feeling of warmth, light-headedness, nausea, ringing within the ears, sweating, turning pale and/ or a cold clammy sensation.

If a person actually experiences syncope (i.e. they faint), the state of unconsciousness only lasts a couple of minutes as once the blood flow normalizes within the brain, the person should return to a state of consciousness.

Ideally, most can recognize the symptoms before they actually faint and can take steps to avoid the physical toll a fainting spell can have. The best thing to do then is to lie down for about 10 minutes or so. This will serve to increase the flow of blood to the brain since we no longer have gravity working against us. An alternative would be to lower your head down so that it rest between your knees. Drinking some water to rehydrate (which increases the amount of blood within your body) may also be of help as well.  Regardless of which intervention steps you choose to stop this reaction with, do not put yourself back at risk by standing up quickly afterwards.

For people who have vasovagal symptoms when they have a bowel movement (which is apparently not rare in those diagnosed with irritable bowel syndrome), try to keep yourself relaxed with deep breathing while crossing your legs and lowering your head in an effort to normalize your blood pressure.

For those who want to prevent any of the symptoms in the first place, try these steps before encountering a situation (like giving blood) that may predispose you to this unpleasant reaction.

Start with getting plenty of sleep the night before, keeping yourself well-hydrated with water and try to avoid standing for extended periods of time.

Lastly, for those who get these symptoms frequently in the course of their everyday activities, your doctor may recommend a number of ways to prevent the pooling of blood to your legs. These can include the use of knee-high compression stockings, the teaching of several simple foot exercises, dietary changes (with possibly the introduction of more salt into your diet depending on other conditions the individual may have) and encouragement telling you to “tense” your leg muscles periodically while standing.

Lastly your doctor may prescribe the drug fludrocortisone or a selective serotonin inhibitor both of which can raise blood pressure or conversely recommend you for a surgical consult to see if a pacemaker can regulate the heartbeat and prevent the vagus nerve from going through its routine.

While this cascade of symptoms is not injurious to your long-term, it can be both frightening and definitely unpleasant to experience so avoidance, if possible, is definitely the right strategy.