The nursing home ran out of mom's medication for over 24 hours. Is this common or is this something that should be reported?

I'd report it, for at least two reasons.

1. Your mother was left in pain. She shouldn't have been. If that was the fault of the system the NH is using, they need to tighten up the system.

2. Suddenly discovering that they did have some after all in their magic cupboard makes me narrow my eyes. You only have the nurse's word for it that the pharmacy supply hadn't been delivered. It's not impossible that only that day's meds mysteriously "went astray" and for "some reason" the staff didn't want to ask for replacements.

But don't make any accusations: report what happened and ask how it will be prevented from happening again.

I would give the administrator the opportunity to address it first before calling the state.
It was terrible that your mom was in pain for that long.
I would ask the administrator to complete an incident report ( an internal document) and ask the admin to bring it to the Center's Quality Assurance Committee for their review.
Then ask then what steps they are going to take so that this type of episode doesn't happen again for anyone in their care. 

Dear EBeach,

I'm so sorry to hear what happened with your mom's pain meds. I would report it as well. That does not seem in line with proper patient care. Its like you said if they had an emergency stash, why wouldn't they use it right away? Your mom needed that medication. I wouldn't let this slide and report it.

I can vouch for pharmacies running out of narcotics as mine does quite frequently. The inventory on opiates is highly scrutinized now. There are different laws going into effect almost monthly regarding opiates.
Next time if, God forbid, this happens have the staff call the NH/rehab doctor, let him know the situation, and ask him/her to write for another pain med- even if it's a different strength. The nursing staff can either give the patient a stronger pill cut in half (the pill must be scored and not a time released formula so it can be cut in half properly) or the pharmacy can cut the pills in half for the NH to administer. The NH should inform the pharmacy that they will only need enough pills to last 2-3 days or long enough for the pharmacy to restock and provide the correct dose to the NH for your mom, but enough to get her through a few days. 

Thank you for all the responses. I called their pharmacy, the pharmacy told me they didn't receive the order for her meds until the day after the nursing home ran out. Also, by the way my mom is in long term care, so they know her meds. I asked the pharmacy if the nursing home needs to run out of her meds to place an order, (I assumed no but still wanted to ask) and they said no, they prefer the orders several days in advance... when it's low. I called the social worker who said she will report all of this to the administrator and that they would investigate it. I also plan to call the ombudsman, I don't fully trust to nursing home to 100% take care of this.

I don't know about reporting one way or the other but when my mom was transferred from the hospital to rehab on a Friday afternoon she was out of luck for over 24 hours on getting her pain meds. I had some and gave them but not until I pitched a b did they get the meds on site.
My guess is that the folks left in charge are caught between a rock and a hard place. They don't want to elevate the problem for whatever reason until you make it more comfortable for them to do so than not.
I got a lot of lip on why it didn't happen properly but bottom line until I complained nothing happened. I hesitate to complain for fear I might make the situation worse but when your loved one is in pain and you are the one trying to help them it makes it very hard to do nothing.

This is totally unacceptable.
Raise it first with the NH staff and if your get no satisfaction go to the state.
Pharmacies do frequently run out of medication which is a good reason to order a few days early for everyone.
Pharmacies tend to run their inventories very low to save money so this can happen a lot. It has happened to us several times with very common drugs not narcotics.
Often the NH staff will "borrow" from another patient till the new supply arrives. i don't know if this is legal or not but it does go on.
As for the emergency stock, every nurse in the place who has access to medications should know about the emergency stock. The nurses on duty when your Mom was admitted should have been questioned.

Note to all caregivers. Make sure you always have a list of your loved ones current medications with you at all times. When admitted to any facility ask the nurses to confirm all medications are available and have been provided. Question any aditions or deletions and understand the reason for the change.
Hospitals generally have their own pharmacy so being out of stock is an not usually an issue, but the time it takes the Dr to write the order, the pharmacy to approve it and send it to the floor can take several hours. You need to do these things on admission because you have be advised not to visit for a couple of weeks when admitting a dementia patient to a NH.

When my sister in law was in rehab they were giving her half of what she was supposed to be getting. Turns out someone was putting down she was getting full dosage and then keeping the half she wasn't getting for herself. Apparently, happens a lot. REPORT it.

EB, who HAVE you discussed this with? I would have assumed that you'd spoken to both the DON and the SW already?

Unbelievable. I am sorry for you and your mom. Definitely report this to both the Administrator and the Ombudsman.