Ask Dr Gary: Supping petrol can hurt lungs

How dangerous is it to get a mouthful of petrol?

If one spits it out and rinses their mouth out with water, there's usually no major issue other than a burning sensation. Just don't smoke!

Emergency department doctors typically see two varieties of gas-guzzler: the hapless adult mouth-siphoning petrol between containers, or the toddler who takes a swig of solvent from a can under the sink or in the garage. Usually the amounts swallowed are tiny, as it tastes foul and really irritates the mouth and eyes.

Longer-term users, ranging from teenage huffers using it to get a short-lived high, to professional fire-breathers doing it for a living, can end up with lots of problems ranging from brain damage and leukemia to cancers of the mouth.

If petrol is accidentally swallowed in a small quantity, and it stays in your stomach, it's not usually dangerous enough to threaten your life.

Petrol isn't absorbed well by the gut and will eventually pass through your intestines and out the other side.

The problem is that it is a strong stomach irritant and can cause vomiting. And when you vomit liquid petrol, it can easily end up in your lungs as a petrol vapor. This is when it becomes dangerous.

In the lungs, petrol vapor takes the place of oxygen and destroys lung surfactant (a natural soapy substance made by the lungs that is crucial in keeping the air sacs from collapsing). Very few people end up with severe aspirations, but when they do, they can die.

Treatment options in the ED are to give oxygen and, in severe cases, intubate patients and put them on a ventilator, and support them while their lungs first fail, then hopefully mend.

It's better not to get a mouthful of petrol in the first place. But if it were to happen to you, contact 0800POISON for detailed advice from the New Zealand National Poisons Centre.