If you run a UK private healthcare clinic, you have almost certainly accepted that appointment reminders are worth doing. The harder question is which method to use. Phone calls feel personal and thorough. Email feels cheap and easy. SMS feels modern but impersonal. Each has an advocate, and most clinics end up choosing based on habit rather than evidence.
That choice matters more than it looks. The wrong reminder method does not just fail to reduce your DNA rate, it quietly costs you staff hours, patient goodwill, or both, while giving you the comforting feeling that you have the problem handled. A clinic that phones every patient the day before is spending real money on labour. A clinic that relies on email may be sending reminders almost nobody opens. In both cases the owner believes reminders are covered, and the no-show rate barely moves.
This guide compares the three methods head to head: what each actually does to attendance, what each costs, and where each still makes sense. By the end you should be able to decide which approach fits your clinic, and know what to look for if you decide to automate.
The real cost of choosing the wrong method
Before comparing the three, it helps to be clear about what you are actually buying. A reminder is not a nicety. It is a revenue-protection tool, and like any tool it has a cost and a return.
The return is straightforward. UK private clinics typically run a DNA rate between 8% and 12% of booked appointments. If you are not sure where you sit, our guide on what a good no-show rate looks like for a UK private clinic sets out benchmarks by specialty. A good reminder system can cut that rate by roughly a third, which for most clinics is worth hundreds to thousands of pounds a month.
The cost is where the three methods diverge sharply. One of them scales for free. One of them costs you a fixed, predictable subscription. One of them costs you a slice of a salaried person's day, every single day, forever. Getting this wrong does not show up as a dramatic failure. It shows up as a receptionist who is always a bit behind, or a no-show rate that never quite improves, and neither of those is easy to trace back to the reminder method itself.
The three methods, compared
Let's take each in turn, honestly, including what each is genuinely good at.
Phone calls
A personal phone call is, in isolation, the most effective single reminder you can give. The patient hears a human voice, has a chance to ask questions, and feels a social obligation that a text simply cannot replicate. For a first consultation worth £150, or a pre-surgical assessment, a call is often worth the effort.
The problem is that phone calls do not scale, and they fail silently. Consider the arithmetic. A clinic running 400 appointments a month that phones each patient the day before is making roughly 20 calls a day. Many go to voicemail, which means a callback or a second attempt. Realistically that is 60 to 90 minutes of a receptionist's day, every working day, doing nothing that generates revenue.
At a modest £13 an hour, that is somewhere around £250 to £370 a month in staff time, and that is before you count the calls that never connect. Voicemail is the quiet killer here: a reminder left on an answerphone is only marginally better than no reminder, and you have no way of knowing whether the patient ever heard it. The personal touch is real, but you are paying for it at full price whether or not it lands.
Email is the method clinics reach for when they want reminders to cost nothing. It is easy to automate, it can carry detailed information, and it leaves a written record the patient can refer back to. On paper it looks ideal.
In practice, email struggles badly in the appointment-reminder context for one reason: people do not reliably read it. Average open rates for transactional and promotional email in the UK sit around 20% to 25%, and click-through rates are typically under 3%. A reminder that four out of five patients never open is not a reminder, it is a filing exercise. Add spam filtering, crowded inboxes, and the simple fact that many patients treat email as something they check at their desk rather than something in their pocket, and email's real-world impact on attendance is weak.
Email is not useless. It is a good channel for the confirmation at the point of booking, where the patient is actively engaged and may want the details in writing, and for anything that genuinely needs length, such as pre-appointment instructions or intake forms. As the primary day-before nudge, though, it underperforms so consistently that relying on it alone is close to relying on nothing.
SMS
SMS sits in the middle of the personal-versus-scalable trade-off, and for appointment reminders that middle is exactly the right place to be.
Three facts make SMS work. Almost every patient carries a mobile phone with them at all times. Text messages are opened at a rate of around 98%, and usually within minutes of arriving. And replying to confirm or cancel takes seconds, which turns silent would-be no-shows into early cancellations you can still fill. A text does not have the warmth of a phone call, but it reaches the patient far more reliably than email and costs a fraction of a call.
Crucially, SMS scales the way phone calls cannot. Sending 20 reminders or 2,000 reminders takes the same amount of human effort once it is automated, which is to say none. That combination, high open rates plus near-zero marginal cost, is why the evidence base has landed so firmly on SMS as the default.
What the evidence actually shows about SMS
It is worth being specific here rather than hand-waving about effectiveness, because the research on this is unusually clear.
A systematic review published in the British Journal of General Practice found that SMS reminders reduce no-show rates by between 25% and 38%. The effect is strongest when the reminder arrives around 24 hours before the appointment: close enough to be top of mind, far enough ahead that the patient can still rearrange their day or tell you they cannot make it.
The mechanism matters as much as the headline number. SMS does not just remind, it prompts a reply. A patient who reads a text at lunchtime and realises they have a clash can reply to cancel there and then, giving you 24 hours to offer the slot to someone on a waiting list. The same patient, faced with an unopened email or a missed call, does nothing, and becomes a no-show. This is why the gap between SMS and email is wider in practice than the open-rate numbers alone suggest: SMS does not only get read, it gets acted on.
For a clinic losing 10% of appointments, moving to 7% through SMS reminders alone typically recovers hundreds of pounds a month, which for most clinics covers the cost of the system several times over. Our full guide to ten proven ways to reduce patient no-shows ranks this as the single highest-impact lever available, ahead of every other intervention.
Cost comparison: staff hours versus platform cost
Put the three methods side by side on cost and the picture is stark. The table below assumes a clinic running 400 appointments a month.
| Method | Reaches the patient | Roughly what it costs per month | Scales? |
|---|---|---|---|
| Phone calls | High when connected, but many go to voicemail | £250 to £370 in staff time, before missed calls | No, cost rises with volume |
| Low, around 20% to 25% open rate | Near zero to run | Yes | |
| SMS | Very high, around 98% open rate | A fixed subscription, typically £100 to £250 | Yes |
The phone-call figure is the one clinic owners tend to underestimate, because it is buried inside a salary rather than showing up as an invoice. It does not feel like a cost. But an hour a day of reminder calls is an hour a day not spent booking new patients, chasing payments, or greeting people at the desk, and across a year that is a meaningful chunk of a full-time role.
Email looks free, and in cash terms it nearly is, but its low open rate means you are largely paying nothing for a result that is close to nothing. SMS is the only method that combines a predictable, capped cost with a reach high enough to actually move your DNA rate. For a system that reliably recovers several missed appointments a month, a fixed subscription in the low hundreds is not really a cost at all, it is a trade that pays for itself in the first week.
When each method still makes sense
None of this means SMS is the only tool you should ever use. The most effective clinics are not dogmatic, they match the method to the appointment.
Use a phone call for high-value or high-stakes appointments. A first consultation worth £150, an initial aesthetics assessment where a deposit is on the line, or any appointment where a no-show is especially costly justifies the staff time. The personal contact also does relationship work that a text cannot, which matters most at the start of a patient relationship.
Use email for confirmations and anything that needs length. At the point of booking, when the patient is engaged, an email is a fine way to send a written confirmation they can save, plus any pre-appointment instructions, directions, or intake forms. It is a supporting channel, not the front line.
Use SMS as your default reminder for everything else, which in most clinics is the overwhelming majority of appointments. The day-before nudge, the confirmation at booking for patients who prefer text, and the easy reply-to-cancel loop are all jobs SMS does better and cheaper than the alternatives.
In other words, the question is not really "which one," it is "which one as the default." For the day-before reminder that determines whether patients actually turn up, the evidence points clearly to SMS, with phone calls reserved for the small number of appointments where the extra cost is justified.
What to look for in an SMS reminder system
Once you have decided SMS should carry the load, the next decision is which system. Not all of them are equal, and a few features separate the ones that quietly work from the ones that create new problems.
A good system sends a confirmation at the moment of booking and a reminder around 24 hours before the appointment, automatically, with no daily manual step. It supports two-way replies so patients can confirm or cancel by text, and it surfaces those replies where your team will actually see them. It handles timing sensibly, so reminders never go out at antisocial hours, and it lets you personalise messages at least to the level of practitioner and clinic name. If you want a deeper walkthrough of the mechanics and the features that matter, our guide on how automated appointment reminders work and what to look for in a system covers this in detail.
There is one more consideration that is easy to overlook and expensive to get wrong: compliance. An SMS reminder involves processing patient data, and in a healthcare context that carries obligations most clinic owners have not fully thought through, from what the message may safely contain to what agreement you need with your reminder vendor. Before you commit to any system, it is worth reading our guide on GDPR and patient SMS reminders for UK clinics, which sets out what a compliant setup looks like and the questions to put to any provider.
The last thing to look for is simplicity. A system that takes fifteen minutes to set up and then runs itself will do more for your no-show rate than a powerful platform that is too fiddly to maintain. The best reminder system is the one you will actually keep using.
Conclusion
The three methods are not really competing on a level field. Phone calls are the most personal and the most expensive, and they fail silently to voicemail. Email is the cheapest and the least effective, opened by only a fraction of patients. SMS is the one method that reaches almost everyone, prompts a reply, and scales without adding staff cost, which is why the evidence has settled on it as the default day-before reminder for private clinics.
The smart approach is not to pick one and abandon the others. It is to make SMS your workhorse, keep phone calls for the handful of high-value appointments that earn the extra effort, and use email for confirmations and anything that needs room. Get that mix right and a 10% DNA rate can realistically fall into the low single digits within a couple of months, without hiring anyone or overhauling your booking system.
How ShowUp helps
ShowUp is software for UK private healthcare clinics that fills cancelled slots from a waiting list by SMS and sends automated appointment reminders, working alongside Cliniko. It sends a confirmation SMS when an appointment is added and a reminder 24 hours before it is due, automatically. Patients can text back, and their replies appear in a Messages inbox in your dashboard for your team to read and act on. Plans are priced by appointments per month, from 300 on Starter to 1,200 on Clinic, with no per-message charges, and setup takes under fifteen minutes with no integration required.
ShowUp is a flat monthly subscription sized to your clinic, with SMS included and no per-message charges. Slot recovery is an add-on with a free trial. Current plan prices are shown when you sign up.
If ShowUp sounds like a fit for your clinic, send us an email.
About the author
Will Kirk is the founder of ShowUp Software Ltd, a UK company that makes ShowUp: software that helps private healthcare clinics recover revenue from cancelled and missed appointments by offering freed slots to a waiting list by SMS, with automated appointment reminders included. ShowUp works alongside Cliniko. Based in Nottingham. ICO Registered: ZC159538. Company Number: 17228859.
Sources
- British Journal of General Practice: Text message reminders for healthcare appointments: a systematic review
- NHS England: Outpatient attendance and DNA data
- ELFT Community MSK Physiotherapy Service: SMS reminder effectiveness study (PMC5699120)