Three numbers explain why SMS still wins. 98% open rate. 90 seconds median read time. 30% click-through on well-crafted clinic messages. No other channel comes close. Email opens at 22%. Push notifications at 12%. Even WhatsApp, which we love, runs at 75-80% in clinical contexts.
The catch: SMS is also the easiest channel to ruin. One spammy campaign and you've trained the patient base to opt out of the channel that drives reminders. Here's the disciplined way to use it.
Table of Contents
- When SMS is the right channel
- When it isn't
- The five message types that work
- Tone and timing
- Compliance basics by region
- Metrics that matter
- FAQ
When SMS is the right channel
- Time-sensitive reminders.
- Confirmation flows requiring immediate action.
- One-tap rebookings.
- Critical clinical alerts (lab result available, etc.).
- Birthday or relationship messages where brevity is the point.
When it isn't
- Long educational content (use email or portal).
- Anything requiring images or formatting.
- Marketing-heavy promotions sent to all patients.
- PHI-heavy messages (use a secure portal).
The five message types that work
| Type | Timing | Conversion lift |
|---|---|---|
| Appointment reminder | 24h + 2h before | Cuts no-shows ~30-40% |
| Confirmation request | At booking | Locks intent |
| Post-visit feedback | 24h after | 3x review velocity |
| Recall reminder | Per specialty cadence | +15-25% return rate |
| Lab/result ready | When result lands | Massive engagement lift on portal |
Tone and timing
- Use the patient's first name and the doctor's name.
- Send between 10am and 7pm local time.
- Keep messages under 160 characters when possible.
- Always include a clear action ("Tap to confirm," "Reply 1 to reschedule").
- Identify your clinic in every message — patients delete unknown senders.
Compliance basics by region
- Capture explicit opt-in at booking or intake.
- Honor opt-outs immediately — STOP / unsubscribe / equivalents.
- Use a registered sender (TCR in the US, equivalent in EU/UK/MENA).
- Maintain a record of consent per patient.
- Don't share lists across clinics without independent consent.
Metrics that matter
- Delivery rate (target: above 96%).
- Click-through rate on actionable messages.
- Opt-out rate (target: under 1% per send).
- Confirmation rate on reminders.
- Cost per actioned message.
FAQ
How much does SMS cost?
$0.01-$0.05 per message in most markets. At 5-7 messages per active patient per year, that's well under $1/patient — versus the no-show savings, easily 30-50× ROI.
Why not just use WhatsApp for everything?
Reach. SMS works without an app, without WhatsApp installed, on any phone. For appointment reminders especially, the ubiquity matters.
Can I use SMS for marketing campaigns?
Sparingly. Reminders and operational messages are universally welcome. Marketing blasts get opt-outs fast. Limit promotional SMS to 1-2x per quarter, max.
How do I capture explicit consent?
At booking and intake forms — a clear checkbox: "I'd like to receive appointment reminders by SMS." Default unchecked; record the timestamp.
What if a patient replies with a question?
Route inbound replies to your shared chat inbox so a real person can answer. Auto-replies that say "this number doesn't accept replies" are a trust-killer.
Should I use shortcodes or long codes?
Long codes are fine for transactional clinic use. Shortcodes are overkill at clinic scale and cost much more.
The summary
SMS is a precision instrument: extraordinary when used for short, action-oriented, time-sensitive moments; corrosive when used as a marketing megaphone. Stick to the five message types that work, register properly, honor consent, and the channel pays for itself many times over. Pair with our no-shows piece for the highest-impact use case.