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Have you ever wondered what
happens to a painkiller, like ibuprofen,

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after you swallow it?

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Medicine that slides down
your throat can help treat a headache,

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a sore back,

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or a throbbing sprained ankle.

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But how does it get where it needs
to go in the first place?

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The answer is that it hitches
a ride in your circulatory blood stream,

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cycling through your body in a race
to do its job

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before it's snared by organs
and molecules designed to neutralize

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and expel foreign substances.

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This process starts 
in your digestive system.

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Say you swallow an ibuprofen tablet
for a sore ankle.

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Within minutes, the tablet starts
disintegrating in the acidic fluids

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of your stomach.

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The dissolved ibuprofen travels
into the small intestine

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and then across the intestinal wall
into a network of blood vessels.

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These blood vessels feed into a vein,

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which carries the blood,
and anything in it, to the liver.

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The next step is to make 
it through the liver.

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As the blood and the drug molecules
in it travel through liver blood vessels,

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enzymes attempt to react with 
the ibuprofen molecules

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to neutralize them.

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The damaged ibuprofen molecules,
called metabolites,

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may no longer be effective as painkillers.

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At this stage, most of the ibuprofen
makes it through the liver unscathed.

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It continues its journey out of the liver,

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through veins,

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into the body's circulatory system.

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Half an hour after you swallow the pill,

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some of the dose has already made it
into the circulatory blood stream.

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This blood loop travels through every
limb and organ,

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including the heart, brain, kidneys,
and back through the liver.

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When ibuprofen molecules 
encounter a location

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where the body's pain 
response is in full swing,

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they bind to specific target molecules
that are a part of that reaction.

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Painkillers, like ibuprofen, block the
production of compounds

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that help the body transmit pain signals.

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As more drug molecules accumulate,

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the pain-cancelling affect increases,

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reaching a maximum within about
one or two hours.

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Then the body starts efficiently 
eliminating ibuprofen,

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with the blood dose decreasing by half
every two hours on average.

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When the ibuprofen molecules detach
from their targets,

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the systemic blood stream carries
them away again.

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Back in the liver, another small fraction
of the total amount of the drug

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gets transformed into metabolites,

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which are eventually filtered out
by the kidneys in the urine.

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The loop from liver to body to kidneys
continues at a rate

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of about one blood cycle per minute,

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with a little more of the drug neutralized
and filtered out in each cycle.

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These basic steps are the same for
any drug that you take orally,

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but the speed of the process

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and the amount of medicine that makes
it into your blood stream

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varies based on drug,

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person,

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and how it gets into the body.

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The dosing instructions 
on medicine labels can help,

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but they're averages based on 
a sample population

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that doesn't represent every consumer.

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And getting the dose right is important.

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If it's too low, 
the medicine won't do its job.

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If it's too high, the drug 
and its metabolites can be toxic.

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That's true of any drug.

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One of the hardest groups of patients
to get the right dosage for are children.

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That's because how they process medicine
changes quickly, as do their bodies.

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For instance, the level of liver enzymes
that neutralize medication

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highly fluctuates 
during infancy and childhood.

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And that's just one 
of many complicating factors.

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Genetics,

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age,

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diet,

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disease,

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and even pregnancy influence the body's
efficiency of processing medicine.

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Some day, routine DNA tests may be able
to dial in the precise dose of medicine

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personalized to your liver efficiency
and other factors,

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but in the meantime,

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your best bet is reading the label

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or consulting your doctor
or pharmacist,

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and taking the recommended amounts
with the recommended timing.