The ad lib medical abbreviation means as desired, or freely, and comes from the Latin ad libitum, roughly at one's pleasure. In a hospital order it signals that a patient can do something, such as walk, eat or drink, as much as they want without a set limit.
You are most likely to see it in admission orders and nursing notes: up ad lib for activity, diet ad lib, or fluids ad lib. It is the opposite in spirit of restrictive orders like NPO, which means nothing by mouth, or bed rest. Written forms include ad lib, ad lib., and occasionally AD LIB in capitals. This guide explains each common use and how ad lib differs from as needed.
At a glance
Stands for
As desired, freely, without a set limitLatin origin
Ad libitum, at one's pleasureWritten as
ad lib, ad lib., AD LIBWhere you see it
Activity, diet and fluid orders; nursing notesCommon phrases
Up ad lib, diet ad lib, fluids ad libDo not confuse with
What the ad lib medical abbreviation tells the care team
Ad lib removes a limit. When a doctor writes it next to an activity or a food order, the patient can choose how much and how often. It is a permission, not an instruction to do more. A patient whose order says up ad lib may walk the hall as often as they feel able, but nobody is required to make them walk.
Because it describes freedom rather than a dose, ad lib is used far more for activity and diet than for medicines today. Older prescriptions sometimes used it for things like a mouth rinse, but modern orders spell out amounts and timing.
Up ad lib and other activity orders
Up ad lib is the most searched form, and it allows the person to leave bed and move around at will. It sits at the free end of a ladder of activity orders.
| Order | What it allows |
|---|---|
| Bed rest | Stay in bed |
| Bed rest with bathroom privileges | Up only to use the toilet |
| Out of bed to chair | Sit in a chair, little walking |
| Up with assist | Walk only with staff help |
| Up ad lib | Move about freely |
A related phrase, OOB ad lib, means out of bed as desired and reads much the same. Even with an up ad lib order, nurses still judge safety, for example after a fall or a new sedating medicine.
Diet ad lib and fluids ad lib
Admission order set: "Diet: regular, fluids ad lib." The patient can eat a normal hospital diet and drink as much as they like. Compare an order such as "fluid restriction 1.5 L per day", which caps intake, often for heart or kidney reasons.
In newborn care you may see feeding ad lib or on demand, meaning the baby is fed when showing hunger cues rather than on a fixed clock. In research and animal studies, ad libitum feeding means food is always available, which is the same idea in a different setting.
Ad lib versus PRN
Both soften a schedule, but they are not the same. PRN, from pro re nata, means as needed and is attached to medicines with a reason and a limit, such as pain medicine every 6 hours as needed. The need has to be there, and there is a maximum.
Ad lib means as desired and usually carries no limit at all. That is why it fits walking and drinking water but is a poor fit for drugs. If a medicine order seemed to say ad lib, a pharmacist would normally ask the prescriber to specify the dose, frequency and maximum.
As desired medical abbreviation in student charting
Nursing and medical assistant students meet ad lib on the first day of reading admission orders. When charting, they record what the patient actually did, such as "ambulated in hall x3, tolerated well", rather than just repeating the order. If the patient's condition changes, the order may change too, so ad lib is reviewed like any other order.
Many schools teach the ad lib nursing abbreviation in a group with other Latin shorthand like PRN, STAT and NPO. The broader list lives in our prescription abbreviations section.
Questions a patient or family might ask
- Does up ad lib mean I should walk, or only that I may?
- Should someone be with me the first time I get up?
- Is there anything I should not eat or drink, even with diet ad lib?
- Will the order change before discharge?
Orders like this are written for one patient at one point in a stay. The nurse caring for you can explain what yours allows today.
Frequently asked questions
What does up ad lib mean in a hospital?
A patient with this order is free to leave the bed and walk around as often as they like. This is the least restrictive activity order, though nurses still watch for safety.
Which abbreviation means as desired in medicine?
The usual abbreviation is ad lib, short for the Latin ad libitum. It appears mostly in diet, fluid and activity orders.
Is ad lib the same as PRN?
No. PRN means as needed and is used with medicines that have a reason and a limit. Ad lib means as desired and normally has no limit, so it suits activity and fluids rather than drugs.
What does diet ad lib mean?
A patient with this order can eat freely from the diet allowed, with no set amount. If a specific diet type is listed, such as low salt, the ad lib applies within that diet.