Prescription Directions and SIG Codes as Severity Evidence in PI Cases

Amar Lunagaria — Co-Founder & Chief Pharmacist, LienScripts | March 4, 2026 | 8 min read

The SIG code on every prescription encodes dosing frequency, route, and clinical urgency that most attorneys overlook. Learn how prescription directions document injury severity as objective pharmacy evidence.

Prescription directions -- the "SIG" field on every prescription -- contain coded clinical intelligence that most plaintiff attorneys never read. A SIG code like "1 tab PO Q4H PRN severe pain" tells the pharmacist exactly how much medication, how often, by what route, and under what clinical circumstances the patient needs it. When decoded and presented as evidence, these directions provide objective, prescriber-documented proof of injury severity that is far more difficult for defense counsel to dispute than subjective pain complaints.

• SIG codes encode dosing frequency, route of administration, and clinical urgency directly from the prescriber
• Higher dosing frequencies (Q4H vs Q8H) objectively document greater pain severity without relying on patient self-report
• LienScripts decodes every SIG code in the pharmacy record, and each case receives a MERIT (Medication Evaluation & Rationale for Injury Treatment) report that translates clinical directions into evidence-ready language
• The transition from scheduled dosing ("Q6H") to as-needed dosing ("Q6H PRN") or vice versa documents clinical progression or regression over time
• Defense counsel cannot credibly challenge prescription directions because they originate from the treating physician, not the patient

What SIG Codes Actually Contain

Every prescription includes a SIG field -- shorthand for the Latin "signetur" (let it be labeled). This field contains the complete dosing instructions the pharmacist prints on the medication label. SIG codes use standardized abbreviations:

• PO -- by mouth (per os)
• Q4H -- every 4 hours
• Q6H -- every 6 hours
• Q8H -- every 8 hours
• QID -- four times daily
• TID -- three times daily
• BID -- twice daily
• QD -- once daily
• PRN -- as needed
• HS -- at bedtime (hora somni)
• AC -- before meals
• PC -- after meals

As Amar Lunagaria, PharmD, LienScripts' Chief Pharmacist explains, "When I see a SIG change from gabapentin 300mg TID to gabapentin 600mg QID over the course of treatment, I am looking at objective, prescriber-generated evidence of worsening neuropathic pain. The prescriber evaluated the patient, determined the current dose was insufficient, and documented that clinical judgment in the prescription itself. No subjective pain diary is more credible than that."

How Dosing Frequency Documents Severity

The Frequency Spectrum

Dosing frequency is a direct proxy for symptom severity. A prescriber who writes Q4H (every 4 hours) is documenting that the patient needs medication six times per day -- the maximum practical dosing interval for oral medications during waking hours. Compare this to QD (once daily), and the difference in documented severity is dramatic.

Consider two patients prescribed oxycodone after a motor vehicle accident:

• Patient A: Oxycodone 5mg Q6H PRN -- four doses per day maximum, as needed
• Patient B: Oxycodone 10mg Q4H -- six doses per day, scheduled (not PRN)

Patient B's prescription documents that the prescriber determined the patient needs twice the dose at 50% more frequent intervals, and the absence of "PRN" means the prescriber determined the pain is constant enough to warrant scheduled dosing rather than as-needed relief. Every element of that SIG encodes a clinical judgment about severity.

Scheduled vs. PRN Dosing

The distinction between scheduled dosing and PRN (as-needed) dosing is a clinical pearl that pharmacy records make visible but most attorneys miss:

• Scheduled dosing (e.g., "Q6H" without PRN) means the prescriber has determined the patient needs the medication at regular intervals regardless of momentary symptom status. This documents continuous, persistent symptoms.
• PRN dosing (e.g., "Q6H PRN") means the medication is available when the patient experiences breakthrough symptoms. This documents intermittent but recurring symptoms.

When a patient transitions from PRN to scheduled dosing for the same medication, it documents worsening -- the intermittent symptoms have become constant.

Route of Administration as Severity Evidence

The route of administration encoded in the SIG also communicates severity:

• PO (oral) -- standard first-line route for most conditions
• SL (sublingual) -- faster onset needed; suggests acute or breakthrough pain
• TOP (topical) -- localized treatment; may indicate more conservative approach
• PR (rectal) -- indicates oral route is not tolerated, often due to nausea from other injury-related medications or GI complications
• INJ (injection) -- failure of oral therapy; documents that less invasive routes were insufficient

A transition from oral to injectable medications -- documented by the change in route code in the SIG -- is objective evidence that the prescriber determined oral medications were no longer adequate for the patient's condition.

SIG Changes Over Time Tell the Clinical Story

The most powerful evidentiary use of SIG codes is tracking changes across the fill history. LienScripts generates a MERIT (Medication Evaluation & Rationale for Injury Treatment) report for every case, providing pharmacist-signed documentation for demand packages that captures the complete SIG timeline.

Escalation Pattern

When SIG codes show escalation -- increased dose, increased frequency, or transition from PRN to scheduled -- the pharmacy record documents progressive injury severity without any subjective input from the patient.

De-escalation Pattern

Conversely, when SIG codes show de-escalation -- reduced dose, reduced frequency, or transition from scheduled to PRN -- the pharmacy record documents clinical improvement. This is equally valuable because it shows the patient is not maintaining maximum medication levels unnecessarily.

Using SIG Code Evidence in Demand Packages

When presenting SIG code evidence in demand packages:

1. Create a SIG timeline -- list every prescription for the same medication chronologically with the full SIG code and the decoded meaning
2. Highlight frequency changes -- show how dosing intervals tightened or loosened over time
3. Flag route changes -- identify any shifts from less to more aggressive routes of administration
4. Note PRN-to-scheduled transitions -- these are among the most powerful severity indicators
5. Contextualize with injury events -- show how SIG changes correlate with accident dates, surgical dates, or imaging findings

Countering Defense Arguments

"The patient is exaggerating pain."

Prescription directions are written by the prescriber, not the patient. The SIG code reflects the prescriber's independent clinical judgment about the appropriate dose, frequency, and route. If the prescriber determined Q4H dosing was necessary, that is a clinician's objective assessment, not the patient's subjective claim.

"The prescriber is just writing what the patient asks for."

Prescribers have independent clinical, ethical, and legal obligations. They assess patients, review imaging, perform examinations, and make clinical determinations. The SIG code is the output of that clinical process. Arguing that a prescriber simply writes whatever the patient requests challenges the prescriber's professional competence -- a position defense counsel is rarely willing to take when that same prescriber may be called as a witness.

Practical Takeaways

Prescription SIG codes are underutilized evidence in personal injury litigation. Every prescription in the pharmacy record contains coded clinical intelligence about severity, progression, and treatment intensity that originates from the treating prescriber. Attorneys who learn to read and present SIG code evidence gain an objective, defense-resistant tool for documenting injury severity that complements subjective pain testimony.

Related Resources

• Refill Patterns as Objective Pain Evidence -- How pharmacy fill data documents pain severity
• Dose Escalation Documents Injury Progression -- Tracking severity through dosing changes
• What Is a MERIT Report? -- Understanding the pharmacist-authored clinical summary