As-needed medication log: what to record each time
How to keep a PRN medication log: what to write down with every as-needed dose, how to note whether it worked and what to bring to your appointment.
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You take a medicine only when you need it, and at the next appointment someone asks how often that was and whether it helped. A short log answers that. You can keep it on paper or in Sam, where an as-needed dose is logged right where you track the rest of your day. This post covers what to write down, how to note whether it worked and what to bring.
What is an as-needed (PRN) medication log?
An as-needed medicine is one you take when a symptom shows up, for example a pain reliever, a migraine medicine, an anti-sickness tablet or a reliever inhaler. A PRN log is a record of each time you did.
It is different from a medication list. A list says what you have been prescribed. A log says what you actually took, when and why. Our post Doctor Appointment Checklist for a Chronic Condition shows where both fit.
What should you record each time you take an as-needed dose?
Several sources describe a similar list. The German drug commission AkdÄ, writing mainly for care homes and clinics, asks for the reason, date, time and amount of every dose, and for effect and tolerability to be checked and recorded regularly. The Migraine Trust and the National Migraine Centre add a second dose and comments. For each dose:
- Date and time.
- Reason: what symptom or situation prompted it.
- Medicine name and strength, as printed on the pack.
- Amount: tablets, puffs or millilitres.
- Effect, as you experienced it.
- Whether you took a second dose. The National Migraine Centre asks for a repeat entry if the same medicine is taken more than once in a day.
- Side effects or anything unusual.
- An optional note, such as sleep, stress or a change in other medicines.
Add over-the-counter products and supplements to the same log. Fill it in close to the dose, not at the weekend for the whole week.
How do you note whether it worked?
You do not need to measure anything. Two options work. One is a 0 to 10 score for the symptom, which is what the National Migraine Centre suggests for headache. The other is a short phrase such as "much lighter after about an hour" or "no change".
Pick the point at which you check, and keep it the same. Then entries can be compared with one another. A diary lets the clinician follow the course of symptoms and therapy, as the German Pain Society puts it. The judging stays with them.
Medication log or medication list: what is the difference?
A list is the plan. A log is the history. Many medication-log templates are built to be printed and filled in. They list the columns but rarely say why the reason and the effect matter. They matter because they are what a clinician cannot guess.
Sam's list is your own overview. In it a medicine is "Daily" with fixed times, repeats every 1 to 12 weeks or months, or is "As needed". It is not an official medication schedule from your health system.
What does a clinician look for in an as-needed log?
Usually three things: how often you needed the medicine, what for and whether it worked. For some medicines they count days with a dose rather than single tablets.
Thresholds exist only for certain groups of medicine. For headache, NHS Scotland's guidance describes overuse as regular use over three months, in someone who already has a headache disorder, on 15 or more days a month for simple pain relievers, or on 10 or more days for triptans, opioids and combination pain relievers. For asthma, the charity Asthma + Lung UK says that needing a reliever inhaler three or more times a week is a reason to contact your GP for an urgent review. Those are statements by those bodies about their groups, not about you. Your log does not set a limit. It supplies the numbers for the conversation. If you are unsure, ask your prescriber what applies. If your reliever is not helping during breathlessness, call your local emergency number (112 in the EU, 999 in the UK, 911 in the US).
If your as-needed medicine is for migraine, Chronic Migraine: How Many Days Count? covers the counting side.
Paper, spreadsheet or phone: how to keep it up
All three work. Paper needs no setup. A spreadsheet is easy to sort. A phone is with you when the headache or the cough starts, which helps with the one habit that matters: filling in the log near the time of the dose.
Late entries are less exact, so a short note now beats a long one later. The choice that you keep up beats the choice that looks best.
Apple Health alone can hold a medication list, log an as-needed dose by hand and export the list as a PDF. In a Sam program diary the dose sits in the same entry as the symptom.
Logging for someone else: what to agree first
If you note doses for a parent or partner, agree first who writes what and who owns the notes. It is simplest if the person logs for themselves and you can read along.
In Sam each person keeps their own list. Through the Care Circle the person chooses what someone else can read, read-only and revocable. Only medications linked to a program the person chooses to share are visible, meaning a program with its own diary, doctor report and monthly questionnaire. You cannot log or edit doses for them.
Log as-needed doses in Sam and bring them to the appointment
You log each as-needed dose right where you track your day, and in the migraine or asthma program the doctor report counts the days you took it.
- Instead of paper: add the medicine in the medication list as "As needed", kept apart from "Daily". The Medications chip on Today logs the dose, with an undo toast.
- Instead of a notes app: in a program diary, such as the program for migraine with its diary and doctor report, the as-needed dose sits in the same entry as the symptom.
- Instead of memory at the appointment: the program's doctor report includes the medications linked to it.
Sam does not ask for reason or effect with the dose, and the medication list has no separate export.
Try Sam HealthSam is a wellness companion, not a medical device. The app does not diagnose, treat, cure or prevent any condition or health state. Always consult qualified professionals for medical decisions.
Related reading
Sources
Updated: October 2026
- AkdAe (German drug commission): Requirements for prescribing and using as-needed medication (German, Arzneiverordnung in der Praxis 1/2017)
- NHS Scotland Right Decisions: Medication overuse guidance
- Asthma + Lung UK: Changes to inhaler prescriptions
- Apple: Add and log medications
- National Migraine Centre: Headache diary
- The Migraine Trust: Headache diary
- Deutsche Schmerzgesellschaft: Pain diaries (German)
- pflege.de: Schmerztagebuch (German)
More on recording and taking it along
Frequently Asked Questions
What does PRN mean on a prescription?+
PRN is the abbreviation prescribers use for as needed: you take the medicine when a symptom appears, not at fixed times. How much and how often is set on the prescription and in the patient leaflet, so ask your prescriber or pharmacist if the label is unclear.
Do I need to log over-the-counter medicines too?+
It helps to include them. A doctor or pharmacist can only look at what they can see, and pharmacy products are easy to forget. Write them in the same log and bring the whole list.
How often should I take an as-needed medicine?+
A log cannot answer that. The amount, the minimum gap between doses and the daily maximum come from your prescriber and the leaflet. What a log gives you is a record of how often you did take it, which is useful to bring to that conversation.
How long should I keep a medication log?+
It depends on why you keep it. The National Migraine Centre suggests a month, or as long as possible, before a headache appointment. pflege.de advises a limited period rather than indefinitely, and agreeing the format with the doctor.
What if I forget to write a dose down?+
Add it as soon as you remember, with what you are sure of, and leave out what you are not. Late entries are less exact, so do not treat a gap as a failure. Just carry on.
Can I show my log to my doctor or pharmacist?+
Yes, that is its purpose. The Migraine Trust and the National Migraine Centre both describe a diary as something to review at the appointment. In Sam, the doctor report of a program includes the medications linked to that program.
Is a phone log as good as a paper one?+
Both work if you fill them in near the time of the dose. Back-filled entries lose detail either way. A phone log is easier to carry and to share, and paper needs no setup.