It won't cause shock, but it may cause the child to shiver, which would tend to make the temperature go up instead of down.

Maybe it will help to have a little understanding of how fever works. Normally, we adjust our body temperature by increasing muscle activity and/or directing more blood flow to the interior of the body and away from the skin (either of which will raise the temperature) or by increasing perspiration and directing more blood flow toward the skin (which will lower it.) The "setpoint" for normal temperature is maintained by a part of the brain called the hypothalamus, that works much like a thermostat.

There are a number of chemical substances that can temporarily reset this "thermostat". Many of these chemicals are produced as part of the response to infection, while some are produced by the invading organisms themselves. When the setpoint is pushed higher, your body "thinks" that its normal temperature is too cold, and it responds by increasing involuntary muscle activity. You may shiver, or, if the change is large and sudden, you may have shaking chills. It's the shaking that causes the fever, not the other way around. At the same time, you "feel cold", even though your body's temperature is perfectly normal, so you crawl under the covers...and that also helps to raise your temperature.
When the signal fades, and the thermostat is reset towards normal, that's when you feel hot and start to sweat, as your body tries to lower its temperature. So saying that you want to "sweat out the fever" is really backwards: you start sweating when whatever was causing the fever has stopped.

What the antipyretic medications do is to block the transmission of the signal to the hypothalamus, and thus prevent the thermostat from being "bumped up". Now, we know that the growth and activity of many viruses and bacteria is slower and weaker at high temperatures. So, by agressively "treating" a fever, you're actually preventing the body's defenses from doing their job.

I think that both Peg and Guest Doc make good points. One thing that is often not appreciated is that the reason some herbal treatments (tea tree oil, garlic) work "as well as" antibiotics is that they ARE antibiotics! And as such, they can have the same "bad" effects of toxicity, development of resistance, etc., as the more familiar "drugs".

Remember also that the body is lots smarter than any doctor OR herbalist. When I prescribe an antibiotic for a child, all I'm really trying to do is to slow down the spread of the "bad" bacteria enough to give the child's natural defenses a chance to catch up and do the real "curing".

Aloha,
Mark