Plumbing and Piping - mildly noisy pipes

When we use toilets, showers or sinks on the second floor of the house, there is a mild "thunk, thunk, thunk" sound as the water runs up the pipes. When the upstairs fixture is shut off (or the toilet tank is filled), there is only a very slight bang--nothing worrisome in itself. I can't tell if this is a classic "water hammer," problem, as the main noise appears to occur while the water is running, and not when it stops. Is this perfectly normal, or should I be concerned? If it is a problem, any general recommendations on what might need to be done? Thank you.

Is this something new? Has it always been there and getting worse? If it is new what has changed? [i.e.] has anybody done anything to the pipes? A little more info. and I may be able to help.

I've noticed it since we've been in the house--about two years. At one point several months ago, I figured it wouldn't hurt to treat it as if it were "water hammer," and I performed the simple procedure whereby you shut the main and open all the fixtures to allow air into the system, etc., and this perhaps alleviated it somewhat, but as of the past couple of months I'm noticing it once again.

I've noticed it since we've been in the house--about two years. At one point several months ago, I figured it wouldn't hurt to treat it as if it were "water hammer," and I performed the simple procedure whereby you shut the main and open all the fixtures to allow air into the system, etc., and this perhaps alleviated it somewhat, but as of the past couple of months I'm noticing it once again.
you can get a knock stopper at lowes or homedepot or a plumping store that will make the noise go away

A "knock stopper"? OK, I'll check that out. Thanks.

(I'm revisiting this post of mine from a year ago. I forgot about the problem for a few months because it subsided, but now it's back.)

When we use fixtures on the upper floor of our home, there's a rapid thunking or thumping noise as the water runs up the pipes. It sounds like it's coming from a vertical pipe that is behind the walls. Then, when the toilet stops filling, for example, there's a mild bang--a classic case of water hammer, I suppose.

I tried to find the "knock stopper" product suggested below, but the only thing I came up with seemed to be specifically for washing machines, and that doesn't appear to be my problem. Maybe I need to go to a plumbing supply store for a larger selection.

Meanwhile, I've tried the procedure where you shut the water main and then open the highest and lowest faucets in the house to allow air into the system, but that doesn't appear to do much. Maybe I'm not doing it quite right--for example, the advice usually says to wait until the water is completely drained from the lowest faucet before closing it and turning back on the water. But it seems to take forever until the last trickle of water emerges from that lowest faucet. Are you supposed to wait for those last drops to drain out? Does it matter? Any tricks to that procedure that might help me get better results?

Might this problem be remedied with water hammer arresters? If so, does it require professional expertise to know exactly where and how to install them? It looks like I may need a plumber, but I at least want to first see if there's anything simple I'm overlooking.

Thanks for any advice on this.