Does within mean before or after? Or does it mean both? For example,
Do not drink or eat within an hour of taking these pills.
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Sign up to join this communityDoes within mean before or after? Or does it mean both? For example,
Do not drink or eat within an hour of taking these pills.
Within is a single word. In the sense of your example, it means something like during, or before the end of:
do not drink or eat during the hour before or the hour after you take these pills.
Consider also:
I want to have been promoted within a year of joining the company.
I want to live within five miles of the office.
Within the boundary of my lands, I am king.
See definition on Merriam-Webster.
Edited to point out that it applies to the hour before as well as the hour after. The other answer is better.
do not drink or eat with in an hour of these pills
'Within' means inside some sort of time frame... so this sentence literally means that you must wait until an hour after eating before taking the pills, and must not eat until an hour after taking the pills.
In my experience, this is very usual advice - I don't think it was intended this way; it could mean you need to wait for an hour after eating before taking the pills, or it could mean that you have to wait for an hour after taking the pill to eat.
I would interpret it as the latter, but it isn't entirely clear.
Example : I am going to reach Tokyo within an hour. specificaly says that it will takeme less than an hour or so to reach tokyo.
In a theoretical analysis of the problems of this kind (that befits a site like this) it is important to separate what follows from the meaning of the words used and what follows from reasonable assumptions that can be made about the subject matter.
In order to do that, let us consider first
I want to live within five miles of the office.
which appeared in one of the answers posted earlier. That sentence clearly does not specify anything as to whether I want to live to the south or to the west, or to the northwest, etc. of the office. So far as the information provided in that sentence goes, the possible locations for my home form the circle that has the radius of five miles and my office as its centre (as has been observed by malach in a comment).
Now suppose that we know that my office is on the shoreline and that to the west of it is the ocean. That would rule out the possibility of my living to the west of the office; the possible locations for my home would now form roughly a semicircle rather than a circle. What is important to note is that this narrowing down of the possibilities has nothing to do with the meaning of within, which hasn't changed between the two versions of the example; the narrowing down of the possibilities is a result of our knowledge of geography which came from some source outside the sentence we are analysing.
Now consider a different sentence, which appeared in the same answer
I want to have been promoted within a year of joining the company.
The word within here is the very same word as in the previous example. Just like in the spatial cases that word does not itself tell us anything about the spatial direction (north, south, etc.), so in this, temporal, case, it does not tell us anything about the temporal direction (before or after). So far as the meaning of the word is concerned, the promotion could be either before or after joining the company. Of course, the idea of one's being promoted before joining the company is absurd, and that's why it normally won't even cross one's mind upon hearing the sentence; we will immediately understand that the promotion that the speaker wants must be within a year after joining the company. But our being able to narrow down the possibilities in this way is a result of something outside the sentence we are considering: our background knowledge of how employment and promotions work.
When we apply these insights to the OP's own sentence,
Do not drink or eat within an hour of taking these pills.
we see that its meaning is not limited to either the hour before or the hour after taking the pills; it covers both. Somebody who knows something about the way these pills are absorbed in human digestive system may perhaps be able to tell us that only one of the two hours really matters, but in telling us that the person would not be analysing the meaning of the sentence itself; the person would be relying on some knowledge that comes from the sources outside it.