In medical shorthand, an “S” with a horizontal line (called a macron) drawn over it is an abbreviation meaning “without.” It comes from the Latin word “sine,” and you will most often encounter it on prescriptions, in handwritten chart notes, or in older clinical documentation. Though it looks cryptic to patients, it is one of a handful of Latin-derived symbols that healthcare professionals have used for centuries to save time when writing orders and notes.
Where the Symbol Comes From
Medical Latin has a long history. For hundreds of years, physicians across Europe wrote prescriptions entirely in Latin, and many of those conventions survived into modern practice as compressed shorthand. The letter “s” with a macron (s̄) is simply the first letter of “sine” with a line over it to signal that the full Latin word is being abbreviated. The practice of placing a macron over the first letter of a Latin word was a common scribal convention, not unique to medicine, but it stuck around in healthcare long after most other fields abandoned Latin.
A paper in the journal Anesthesia Progress noted that abbreviations like s̄ for “sine” are among the “old-fashioned Latin abbreviations” still in circulation in clinical settings, and recommended their elimination to reduce medication errors.1Europe PMC. It’s time to throw out old-fashioned Latin abbreviations Despite that recommendation, the symbol persists in many handwritten prescriptions and clinical notes, especially among older practitioners or in teaching environments where students are still expected to learn these conventions.
How It Appears on Prescriptions
On a prescription or a medication order, s̄ typically modifies whatever follows it. If a doctor writes “s̄ food,” it means “without food,” indicating the medication should be taken on an empty stomach. If you see “s̄ nausea,” in a chart note, the clinician is recording that the patient did not experience nausea. The symbol functions like a compact negation marker, telling the reader that whatever comes after it is absent.
In practice, the full instruction on a prescription is rarely just s̄ by itself. It usually appears alongside other Latin abbreviations that together form a dosing instruction. A prescription might read something like “1 tab PO BID s̄ food,” which translates to “one tablet by mouth twice daily without food.” Each piece of that instruction is shorthand: PO is “per os” (by mouth), BID is “bis in die” (twice a day), and s̄ is “sine” (without). To a pharmacist trained in these conventions, the whole string reads as a single coherent instruction. To a patient glancing at their prescription, it can look like alphabet soup.
The Family of Latin Abbreviations It Belongs To
The s̄ symbol does not exist in isolation. It belongs to a small cluster of single-letter Latin abbreviations that all follow the same convention: one letter plus a macron. Understanding the whole group makes each individual symbol easier to remember.
- s̄ (sine): without
- c̄ (cum): with
- ā (ante): before
- p̄ (post): after
These four cover the most common modifiers a clinician needs when jotting down quick notes. “c̄ food” means with food. “ā meals” means before meals. “p̄ surgery” means after surgery. Together they form a tiny grammar for writing fast medical instructions. You might also encounter “ss̄” (from the Latin “semis”), meaning “half,” though that one is more commonly seen in older pharmacy notation than in modern clinical notes.
Outside this group, many other Latin abbreviations persist in medicine: “PRN” (pro re nata, as needed), “QID” (quater in die, four times a day), “NPO” (nil per os, nothing by mouth), and “Rx” (from the Latin verb “recipere,” to take). The macron-over-a-letter abbreviations like s̄ are just the most visually distinctive members of a much larger Latin vocabulary embedded in clinical practice.
Why This Causes Confusion for Patients
If you have ever looked at your own medical records through a patient portal and found them baffling, you are far from alone. When physicians began writing notes with these abbreviations, the intended audience was always another healthcare professional. Patients were never expected to decode them. That dynamic has shifted dramatically in recent years. Open-notes policies and electronic health records now give patients direct access to what their doctors write, and the gap between clinical shorthand and everyday language is suddenly a real problem.
Physicians themselves have worried about this. Research into patient-facing medical notes found that doctors expressed concern that patients would find their notes “confusing and offensive” and that shorthand, jargon, and even typographical errors would appear unprofessional when viewed by non-clinicians.2PubMed. Patient-centric medical notes: Identifying areas for improvement in the age of open medical records Those concerns are not unfounded. A symbol like s̄ that is perfectly clear to a pharmacist is genuinely opaque to someone who has never seen it before. Add in the fact that handwritten versions can be ambiguous (is that a macron or just an accidental pen stroke?), and the potential for misunderstanding grows.
That said, outright confusion may be less common than doctors fear. A large study involving more than 4,500 patients who read their primary care clinic notes online found that roughly 88% disagreed with the statement that their notes were “more confusing than helpful.”3PubMed Central. Characteristics of Patients Who Report Confusion After Reading Their Primary Care Clinic Notes Online Still, a small but meaningful share of patients did report confusion, and abbreviations like s̄ are exactly the kind of thing likely to trip up someone in that group. If you are reading your own chart and see a symbol you do not recognize, the safest move is always to ask your pharmacist or physician for a plain-language explanation rather than guessing.
The Safety Problem With Medical Abbreviations
The bigger concern with s̄ and its relatives is not just patient confusion but outright misinterpretation by other healthcare workers. Medication errors linked to abbreviation mix-ups are a well-documented problem. The most dangerous confusion involving s̄ happens when it is misread as something else entirely. In sloppy handwriting, s̄ can be mistaken for the numeral 5, or the macron can be missed altogether, changing the meaning of an instruction from “without” to something that does not make grammatical sense, prompting the reader to guess. Guessing in medicine is where errors happen.
The Institute for Safe Medication Practices (ISMP) maintains a list of error-prone abbreviations, symbols, and dose designations that it recommends healthcare organizations stop using. Several Latin abbreviations appear on that list, precisely because their handwritten forms invite misreading. The Joint Commission, which accredits hospitals in the United States, has its own “Do Not Use” list of abbreviations that accredited facilities must avoid in handwritten and pre-printed orders. While s̄ is not on the Joint Commission’s short official list (which focuses on the most dangerous offenders like “U” for units and “IU” for international units), it falls within the broader category of Latin abbreviations that patient safety organizations have discouraged for years.
The core issue is that abbreviations save the writer time but shift the cognitive burden to the reader. When the reader is a pharmacist filling a prescription at speed, or a nurse pulling medication at 3 a.m., that shifted burden has real consequences. Writing “without” instead of “s̄” takes a fraction of a second longer but eliminates an entire category of misreading.
Are These Abbreviations Being Phased Out?
In electronic health records, much of this shorthand has already become less relevant. When a physician enters a prescription through an EHR system, the software typically generates standardized instructions in plain English. The computer does not need Latin shorthand because it has dropdown menus and structured fields. “Take one tablet by mouth twice daily without food” gets printed on the pharmacy label regardless of what abbreviation the doctor might have typed or selected internally. This shift has quietly reduced the number of times a patient or pharmacist encounters symbols like s̄ on actual prescription paperwork.
But the transition is uneven. Handwritten prescriptions are still legal in many jurisdictions, and some practice settings (especially smaller clinics, long-term care facilities, and certain specialties) still rely on them. Clinical notes in teaching hospitals often include Latin abbreviations because medical students learn them during training and use them in their own documentation. And even within EHR systems, the free-text portions of a note (the physician’s narrative assessment, the plan section, quick bedside notes) may still contain s̄ and its relatives because old habits persist.
The recommendation from patient safety organizations has been consistent for years: spell it out.1Europe PMC. It’s time to throw out old-fashioned Latin abbreviations Write “without” instead of s̄, “with” instead of c̄, “before” instead of ā. The argument is not that these abbreviations are inherently wrong but that the tiny time savings for the writer is not worth the risk to the reader. Progress has been real but slow. Surveys of clinical documentation continue to find Latin abbreviations in use, even in facilities that have formally banned them.
How to Read the Abbreviation if You Encounter It
If you are staring at a medical document and see what looks like an “S” with a line over it, the meaning is almost certainly “without.” Context should confirm this. If the note says something like “pt tolerating meds s̄ side effects,” it means the patient is tolerating medications without side effects. If a prescription label includes “s̄ food,” the instruction is to take the medication on an empty stomach, or at least not with a meal.
The macron (the line over the letter) is the key visual feature. Without that line, a lowercase “s” in medical shorthand could mean many things depending on placement. With the macron, it specifically signals the Latin abbreviation for “without.” If you see a line over a “c” or a “p” in the same document, those follow the same logic: c̄ is “with,” p̄ is “after.”
One thing to watch for: in some handwriting styles, the macron over the s̄ can look like a tilde (~), which gives the symbol a slightly different appearance but the same meaning. Some older medical textbooks even used a small superscript bar that looked more like a tiny dash than a full line. These are just variations in how the symbol gets rendered by hand, not different symbols with different meanings.
Similar-Looking Symbols That Mean Different Things
One reason patients get tripped up by s̄ is that medicine is full of single-letter abbreviations that can look alike, especially in hurried handwriting. A few worth knowing:
- Ś or S with an accent: Not a standard medical abbreviation. If you see this, it is likely a handwriting artifact or a different notation system.
- Sx: Often shorthand for “symptoms” (sometimes also “surgery,” depending on context).
- SS: Can mean “one-half” (from the Latin “semis”) in older pharmacy notation, though this abbreviation is now on most “do not use” lists because it can be mistaken for the number 55.
- S1, S2: Heart sounds (first heart sound, second heart sound), used in cardiology and physical examination notes.
None of these have a macron. The macron is what specifically identifies s̄ as the Latin “sine.” If the symbol you are looking at lacks that horizontal line, it is probably one of these other abbreviations, and the meaning depends entirely on context.
When You Should Ask for Clarification
If you pick up a prescription and the label contains abbreviations you cannot parse, your pharmacist is the right person to ask. Pharmacists are trained to interpret prescription shorthand and catch errors in it. They are also, in many cases, the last safety check before medication reaches you. A quick question at the counter is far safer than an internet search that might match the wrong abbreviation.
For clinical notes accessed through a patient portal, many health systems now offer a messaging feature where you can ask your physician or care team what a specific note means. Some EHR systems have even started building in hover-over definitions for common abbreviations, though coverage of Latin shorthand varies. If your portal does not offer that, a phone call to the clinic is perfectly reasonable. Physicians who write abbreviated notes generally expect that someone might need them translated, and a patient who asks for clarity is doing exactly what safety advocates recommend.
The broader trend in healthcare communication is toward plain language. Many hospitals now train residents to write notes as though the patient will read them, because increasingly, the patient will. That shift has not eliminated Latin abbreviations overnight, but it has made clinicians more aware that s̄ and its cousins are jargon, not universal language. Until that transition is complete, knowing that s̄ means “without” puts you ahead of most patients who encounter the symbol and simply skip over it.