Ibuprofen – why is it recommended to take 2 x tablets every 4 hours but not allowed 1 x tablet every 2 hours. Surely it would make the pain relief longer lasting?



Ibuprofen – why is it recommended to take 2 x tablets every 4 hours but not allowed 1 x tablet every 2 hours. Surely it would make the pain relief longer lasting?

In: Biology

There’s a few reasons.

First, there’s the convenience. It’s much easier to remember every four hours to take two tablets than it is to take one every two, plus it gets it over with. Most people don’t want to set an alarm every two hours to keep the dosage proper, they just wait for the signal to take more pills if after four hours the pain starts coming back.

Then there’s the dosage level. If you take one, and then take another two hours later, you’re only getting 50% of best possible pain relief for the first two hours. When you’re hurting enough for two tablets as the “full dose”, you’re going to want that pain relief NOW, so you take the full dose at the start.

Next, a lot of reasons to take Tylenol are completely solved by the first dose. A lot of headaches or other aches go away completely on a single two-tablet dose, so you don’t have to come back two hours later to dose up again. And you should really only take pain meds when you actually need them, not take them sequentially over a period of hours if the pain has already been taken care of.

What the other comment said, but a bit of clarification.

When you take pills, the pills are made mostly of filler ingredients. These are made so that the active ingredients will slowly dissolve into your system, as opposed to getting the full benefit from one or both immediately. Thus, only 50% for 4 hours as opposed to 100% for 2 hours.

To simplify: the dose of the drug is like the power to kill the pain, the half-life is the time the drug stays in your body and kills the pain. If you take half of the dose every two hours you are lacking pain-killer power and the drug is not worn out when you take the new pill so it is totally useless.

Hope it helps 🙂

Some of it is about the absorbance rates to the drug into your blood stream when compared against the ‘effective dose’ (while also not producing harmful side effects) needed to actually trigger the receptor responses. Now couple all that craziness with your liver turning it into a form that your kidneys can flush out. (This is probably the simplest way one can talk about pharmacokinetics).

So you have to take enough to take effect, while it’s fighting a constant ‘draining’ effect of it getting removed from your body due to liver/kidneys. If you take less than the lowest does it might have a reduced effect. So you might reduce your benefit meanwhile still putting pressure on your liver/kidneys.

I tell my patients “you can take 400 mg every 4 hours, 600 mg every 6 hours, or 800 mg every 8 hours.”

Easy to remember and you can plan your dosing based on activities/ sleep.

Where do you see that you can’t take 1 tablet every 2 hours?

I usually take 1 to see if it causes a placebo effect. If the pain/headache goes away in less than 30 minutes it is probably not from the pill. If I still have a headache but not as bad I will take one more in 30 minutes. Then do the 2 in 4 hours if needed. But with tylenol right now because I cant take aspirin or ibuprofen for a few months.

>… not allowed 1 x tablet every 2 hours.

Who says? Where is that written?

2 words: Blood Level. The idea is to get enough of the medicine into your blood at one time to have an effect. Most drugs have a linear relationship of medication dose and medication effect but they also tend to need to get over a certain threshold before they have any noticeable effect. So 2 ibuprofen gets 400mg into you at once which then gets eliminated over a predictable amount of time until your blood level drops to the point that the manufacturer recommends another dose to get your blood level back up to an effective level.

Once you have it up to an effective level, yes, you could take one every 2-3 hours and probably achieve the same thing, but that is making the directions unnecessarily complicated.

Here’s a slightly different question for any pharmacists on this thread: When I was going through menopause, for several weeks I bled so heavily that I literally could not leave the house for more than an hour or so. I became depressed and finally called my doctor’s office for help.

The nurse practitioner who took my call told me to take a boatload of ibuprofen according to a certain schedule. Offhand I can’t remember what dosage she recommended, but it was significantly above what’s listed on the label. It worked!

But it seems counterintuitive, because ibuprofen is an NSAID, which you’re not supposed to take if you have a bleeding tendency. So how did it stop extraordinarily heavy menopausal bleeding? And why was it safe to do that if it’s not safe to go over the recommended dosage for pain relief?

naproxen sodium (aleve) has the same mechanism of action of ibuprofen in a round about way, and lasts 24 hours.

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