Over-the-counter diphenhydramine, for instance, at least in my country, says adults can take “1 to 2 tablets every 4 to 6 hours.”
If you decide “my symptoms aren’t so bad; I’ll just take one” and then two hours later your symptoms are still bad (or worse), is it safe to take a second tab then? And if you do, should you wait until “4 to 6 hours” after taking the first tablet or the second to take an additional tablet? Does it depend on the drug? (Maybe it’s fine for diphenhydramine but not for ibuprophen?)
I’d imagine blood levels of any particular drug tend to quickly spike and then exponentially decay back to undetectable levels. If you take two tabs, I’d imagine that graph is just twice as tall. If you wait a couple of hours between tabs, it’s got two spikes and the second is a little higher than the first (but not as high as the two-tabs-at-the-same-time spike.)
If the concern is total concentration of drug in the bloodstream at any one point, a second tab a couple hours later is less of a concern than two tabs at the same time. If the concern is total area under the curve, then probably there’s no difference between two tabs at the same time and a couple of hours between. If the concern is total time spent with a blood concentration of such-and-such, I could see there being more concern with taking a second tab just a couple of hours after the first.
And maybe there are other effects that I’m not aware of. Maybe if the blood concentration kicks up to two-tabs-at-once levels, the liver kicks into high gear, clearing the drug out quicker, but if you go a couple of hours between tabs, the liver neve kicks into high gear or some such.
And maybe this question hasn’t even been well studied and maybe there’s not really any good answer. But if there is, I’m curious.
OP, please don’t take medical advice from strangers on the internet. The most confident voice here could be a 12-year old who heard about the medication you’re taking on House MD reruns.
Your country may have a state-organised information line to give you advice about medication. You could call and get an authoritative answer to your question. Or you could ask the staff at any retail chemist. They’ll know, or be able to look it up.
Usually I agree here, but this is completely silly in context. We are all perfectly capable of helping OP interpret and follow the directions, because you don’t need to have eight years of medical experience to understand the instructions on the back of the medication box. We’re also talking about over-the-counter medicine here, and it’s basically guaranteed safe for all but the most excessive doses, which OP is not in any danger of exceeding because they’re asking if its okay to take a second pill, when the box already said you can take two simultaneously every “x” hours.
OP is not in any danger of exceeding because they’re asking if its okay to take a second pill, when the box already said you can take two simultaneously every “x” hours.
If OP is unsure about those instructions, OP probably isn’t sceptical enough to evaluate advice from internet randos.
I’ve been seen by worse attendings in my time, but your point is valid.
Look I’m not a doctor but if your meds say take 1-2 tablets every 4-6 hours, and you take one then another a few hours later you are still following the directions.
On a related tangent, why do I, a 220 lbs 6’2" male have the same aspirin dose as a 120 lbs women.
For the tangent, it’s because if they told you how to calculate how much to take based on weight, at least 30% of consumers would fuck it up and take the wrong amount. So they divide it into children under 12 and the rest of us instead.
I’d go 50%. Weight based dosing is not human friendly at all.
More weight doesn’t necessarily mean much more volume of blood compared to someone your height and slimmer.
It’s a thing. For example, Americans are presumed being overexposed to drugs compared to 50 years ago because the average weight has gone up 11kg but height remains mostly the same. There’s reviews.and.maybe one day refreshes, but it’s not really a problem. That ndicates how wide those ranges are for drugs that dose on surface area or weight. The more precise people need to be, the more height, age, metabolism, etc. is factored over weight ballparking.
And then you got OP’s over the counter stuff that doesn’t even bother with that detail. But it would take someone like me around 300–350 100mg aspirin to get in risk of lethal dose and I’d have stopped noticing improvements afer a small few anyway. In short, without prescription, OP will not be given a quantity of drugs in one packet that could cause any degree of harm or effect—mqybe their bowel movements—if taken all at once. Imagine suicide and murder rates lol.
A way that I find helpful to answer questions like this is to look backwards when taking multiple doses:
“If I were to take another pill now, would I have had no more than 1-2 pills in the last 4 hours?”
The pharmacokinetic questions are outside the scope of what the patient should be trying to figure out when taking a drug. That was the responsibility of the drug label writer and (if applicable) the prescribing physician and/or pharmacist. Yours is to faithfully follow the instructions, not make assumptions about drug residence time or loading doses.
That’s a pretty reasonable perspective that will serve most people well.
This is a question for a pharmacist. I am not a pharmacist.
DPH is not a 100% safe drug, but looking at how people abuse it with 32+ pills at once, you are at low risk taking one every few hours. It will make you drowsier and it may be unsafe to operate a car because it generally causes a brain fog and poor cognitive function.
If your symptoms are not alleviated by taking one every 4-6 hours, you should be considering an alternative treatment for your issues instead of increasing the dose.
looking at how people abuse it with 32+ pills at once
Careful about the survivor bias, there.
You have a point but 28-32 pills or 700-800mg is pretty much the standard abuse amount. It is understood that 1g is where you are at the higher risk of death and 2g is basically suicide. There obviously is risk of organ damage with regular use of higher than therapeutic doses and definite risk of regular use at the higher “recreational” doses. There is some medical findings that any amount of regular use is damaging.
So if we consider 700mg the upper limits of a single dose with low short-term risk, a daily consumption of 200mg over 16 hours(1x25mg every 2 hours) is far safer and still within the recommended dose of 1-2 per 4-6 hours.
There are reliable sources of drug information intended for professionals online, for example this AHSP monograph for pseudoephedrine. There’s a pharmacokinetics section with times to peak plasma concentration, half life, and a description of how the drug is eliminated from the body.
If you understand what those terms mean, you can probably make an educated guess as to what will happen when you split a dose as you propose. I’m going to guess that it’s really unlikely to be dangerous with most OTC drugs because those usually have large safety margins, but if you want a reliable answer to that, there’s probably a medical professional you could ask instead of random dogs on the internet.
I wouldn’t worry about it. I’d just make sure to wait the minimum time (in this case, 4 hours) after the second pill, before taking two more. I’d avoid taking 1 pill every 2 hours long-tem, but wouldn’t worry about it for the first dose(s).
Disclaimer: I’m just a random person on the Internet, not a doctor.
Sometimes I’m like you, some headache, I take one paracetamol/acetaminophen, and 2h later take another one. If it still hurts, I’d take one after 2h, or 2 after 4h.
Does 2 pills every 4h is the same than 1 pill every 2h ? I guess it depends on why, if you have a headache, taking 2 at the same time can certainly act faster/better to diminish it?
If you need additional pain relief, it’s better to take an additional drug, rather than more of the same one. I was only able to sleep with an extremely painful ear infection, because I used both paracetamol and ibuprofen. (Recommended to me by the pharmacist who was on night duty when I went out to get something so I could sleep)
AFAIK a larger dose won’t have a stronger effect, but merely be longer lasting, to get more relief you need something that has a similar effect but works differently.
And obviously, combining drugs on your own is not a good idea. While ibuprofen+paracetamol is known to be safe, drugs can interact. As such, when I doubt, ask a pharmacist/doctor.
True for taking one ibuprofen and one paracetamol et the same time, it works great for pain or headache, I often do it.
I don’t know for sure, but that would be my assumption. I would be willing to take the second pill without worry.
i recently saw 10mg cetirizine hydrochloride 365ct for $18 (0.05 ea) . not too pricey. although, i havent researched it.
