Key Terminologies in Pharmacovigilance Explained (ADR, AE, SAE, SUSAR, ICSR Guide)

Pharmacovigilance involves monitoring the safety of medicines and identifying adverse effects associated with drug use. To understand drug safety reporting, it is important to learn the key pharmacovigilance terminologies used in clinical trials and post-marketing surveillance.

In this guide, we explain important pharmacovigilance terms such as Adverse Event (AE), Adverse Drug Reaction (ADR), Serious Adverse Event (SAE), SUSAR, ICSR, signal detection, and risk management with practical examples for beginners.

Core Pharmacovigilance Terminologies Explained with Examples:

👉 Adverse Drug Reaction (ADR)

Any unwanted, untoward, undesired medical occurrence after the drug administration and which does have a casual relationship with the treatment.

Example: A patient develops a rash after taking penicillin.
Here, the rash is caused by the drug → ADR.

To learn more about ADR types and assessment methods, read our detailed guide on Adverse Drug Reactions (ADR): Types, Minimum Criteria, and Challenge–Dechallenge–Rechallenge.

👉Adverse Event:

Any unwanted, untoward, undesired medical occurrence after the drug administration and which does not necessarily nave to have a casual relationship with treatment.

Example: A patient taking a cholesterol-lowering drug (statin) catches the flu.

The flu happened after drug use, but it is not caused by the drug → AE.

👉Side Effect:

Any unwanted,untoward, undesired medical occurrence after the drug administration and it is irrelevant to the dose.

Example: Nausea after taking high doses of opioids.

The nausea is a known effect of opioids → Side effect.

👉Serious Adverse event:

Any unwanted,untoward, undesired medical occurrence after the drug administration and which leads to the seriousness criteria.

The seriousness criteria:

Death/fatal
Hospitalization
Congenital anomalies/birth defect
Disability
Medical significance
Life threatening

For a clear explanation of seriousness criteria, read our guide on Seriousness vs Severity in Pharmacovigilance.

👉Suspectedly Unexpected Serious Adverse Event(SUSAR):

Any unwanted,untoward, undesired medical occurrence after the drug administration and its nature, severity and intensity not in accordance with the authorized product label.

👉Drug Abuse:

It is an intentional, inappropriate excessive use of any medicinal product not for medical purpose but used for personal pleasures.

Example: Cocaine, Heroin, Morphine

👉Drug Misuse:

It is the intentional use for a therapeutic purpose by a patient or consumer of a product-over-the-counter or prescription other than as prescribed or not in accordance with the authorized product label.

Example: A patient takes double the prescribed dose of painkillers to relieve severe pain → Drug misuse.

👉Drug Off-label Use:

It relates to situations where a healthcare professional intentionally prescribes, dispenses or recommends a product for a medical purpose not in accordance with the authorized product information.

Example: Using propranolol (approved for hypertension) to treat anxiety → Off-label use.

👉Drug Overdose:

It is an intentional or unintentional excessive use of any medicinal product more than maximum recommended dose it can be risk to the subjects

Example: Taking 10 tablets of paracetamol at once to relieve severe pain → Overdose (risk of liver damage).

👉Medication Error:

It is an unintentional failure in the treatment also known as physician error, prescription error.
Example: Prescribing insulin 10 units instead of 1 unit due to a typo → Medication error.

👉ICSR (Individual Case Safety Report):

A report documenting one or several suspected adverse reactions in a single patient at a specific point in time, usually reported to regulatory authorities in a standard format.

You can learn the full workflow in our article on ICSR Processing in Pharmacovigilance: Step-by-Step Workflow.

👉Signal:

Reported information on a possible causal relationship between an adverse event and a drug, unknown or incompletely documented previously.

Learn how signals are detected in pharmacovigilance databases in our detailed article on Signal Detection in Pharmacovigilance.

👉Risk Management Plan (RMP):

A detailed plan to identify, characterize, prevent or minimize risks related to drugs and assess effectiveness of risk minimization measures. (Regulatory requirement in EU and other regions.)

👉PSUR / PBRER:

Periodic reports that provide a comprehensive, scientific evaluation of the benefit–risk balance of a medicinal product. PSUR is the older format; PBRER (Periodic Benefit-Risk Evaluation Report) is the ICH harmonized version used globally.

👉Causality Assessment:

Process of evaluating whether there is a casual relationship with drug and caused an adverse event, based on clinical evidence and criteria (time relationship, dechallenge/rechallenge, alternative causes).

Read our detailed explanation of Causality Assessment in Pharmacovigilance.

👉MedDRA:

Medical Dictionary for Regulatory Activities — a standardized medical terminology used to code adverse events for regulatory reporting.

To understand medical coding in pharmacovigilance, read our guide on Medical Coding in Pharmacovigilance (MedDRA Explained).

👉Expedited Reporting:

Requirement to submit serious and unexpected adverse reactions (like SAEs and SUSARs) to regulatory authorities within a defined short timeframe (e.g., 7–15 calendar days).

👉Pharmacoepidemiology:

Study of use and effects of drugs in large populations, used to detect and quantify safety issues not observed in clinical trials.

👉Risk Minimization Measures (RMM):

Actions intended to reduce the occurrence or severity of adverse reactions for a drug, such as warnings, contraindications, educational materials, or restricted distribution programs.

👉Post‑Marketing Surveillance (PMS):

Ongoing monitoring of safety after drug approval, encompassing spontaneous reporting, periodic reports, and targeted safety studies.

👉Expectedness / Unexpectedness:

An adverse reaction is considered unexpected if its nature, severity, specificity, or outcome is not consistent with the applicable product information (e.g., Summary of Product Characteristics (SmPC) for a marketed product or Investigator’s Brochure (IB) for an investigational product).
If the reaction is consistent with the product information, it is expected.

Example (Expected):A patient experiences nausea after taking Drug A when nausea is already described in the official product label → Expected.

Example (Unexpected):A patient develops a severe neurological disorder that is not described anywhere in the product label or IB → Unexpected.

👉Listedness / Unlistedness:

Listedness refers to whether an adverse reaction is already included in the Company Core Safety Information (CCSI) or core safety document for a marketed product.
Listed: The reaction appears in the company’s safety reference information.
Unlisted: The reaction does not appear in the company’s safety reference information.

Note: Listedness is not directly used for expedited reporting (that uses expectedness/unexpectedness) but is used in periodic and aggregate safety reporting (e.g., PSUR/PBRER).

Example (Listed):Drug B’s core safety document includes headache as a known reaction → headache is listed.

Example (Unlisted):Drug B’s safety document does not include a report of pancreatitis → pancreatitis is unlisted.

Understanding the difference between an Adverse Drug Reaction (ADR) and a side effect is important in pharmacovigilance. Although these terms are often used interchangeably, they differ in causality, predictability, and regulatory reporting. The table below summarizes the key differences clearly.

Parameter	Adverse Drug Reaction (ADR)	Side Effect
Definition	A harmful and unintended response to a drug with a reasonable causal relationship	An unintended effect of a drug related to its pharmacological action
Causality	Causality is required	Causality is not always required
Predictability	Often unpredictable	Usually predictable
Dose Relationship	May or may not be dose-related	Often dose-related
Severity	Can range from mild to life-threatening or fatal	Usually mild to moderate
Regulatory Importance	Mandatory reporting in pharmacovigilance	Reported mainly if serious or unexpected
Clinical Impact	May require treatment modification or drug withdrawal	Usually manageable without stopping the drug
Preventability	Often not preventable	Often preventable by dose adjustment
Frequency	Relatively less common	More common
Example	Anaphylaxis after penicillin administration	Drowsiness with antihistamines

Relationship Between Adverse Event (AE) and Adverse Drug Reaction (ADR)

All Adverse Drug Reactions (ADRs) are considered Adverse Events (AEs) because they occur after the administration of a medicinal product. However, not all Adverse Events are Adverse Drug Reactions, as an AE does not necessarily have a causal relationship with the drug.

An ADR requires a reasonable possibility that the medicinal product caused the reaction, whereas an AE only requires a temporal association with drug administration.

💯Understanding pharmacovigilance terminologies is essential for accurate case processing, regulatory compliance, signal detection, and patient safety. These concepts form the foundation of daily PV activities across clinical trials and post-marketing surveillance.

Key Takeaway:

All Adverse Drug Reactions (ADRs) are Adverse Events (AEs),

but not all Adverse Events are Adverse Drug Reactions.

Frequently Asked Questions (FAQs)

1. What is ADR in pharmacovigilance?

An ADR is a harmful and unintended response to a drug where a causal relationship with the drug is suspected.

2. What is the difference between AE and ADR?

An Adverse Event (AE) is any medical occurrence after drug use, while an Adverse Drug Reaction (ADR) has a suspected causal relationship with the drug.

3. What is an ICSR in pharmacovigilance?

An Individual Case Safety Report (ICSR) is a structured report describing adverse reactions experienced by a patient.

4. What is a SUSAR?

A SUSAR is a Suspected Unexpected Serious Adverse Reaction reported during clinical trials.

Key Terminologies in Pharmacovigilance Explained: Beginner-Friendly Guide