March 2026

Volume 12 - Issue 01

Why reporting side effects matters: Understanding pharmacovigilance.

Medicines play a vital role in preventing and treating diseases, improving the quality of life, and saving lives. However, no medicine is entirely free of risks. Even after rigorous clinical trials, some side effects (also known as adverse drug reactions, ADRs) may only become apparent when a medicine is widely used by larger and more diverse populations. This is where pharmacovigilance becomes essential.

What is pharmacovigilance?

Pharmacovigilance (PV) is defined by the World Health Organization (WHO) as the science and activities related to the detection, assessment, understanding, and prevention of adverse effects or other medicine-related problems.

Why was pharmacovigilance created?

Pharmacovigilance was developed to protect public health and improve patient safety. Historical events, such as the thalidomide tragedy in the 1960s — where a medication given to pregnant women caused severe birth defects — highlighted the need for robust post-marketing surveillance of medicines. In response, regulatory authorities such as the World Health Organization (WHO) and national drug agencies established pharmacovigilance systems to:

• Identify new or rare side effects not detected during clinical trials.
• Evaluate the severity and frequency of known adverse effects in larger populations.
• Take appropriate actions when risks outweigh benefits, such as updating product labels, issuing safety warnings, or withdrawing medicines from the market.

Why is reporting side effects important?

Reporting side effects of medicines—by healthcare professionals, patients, or manufacturers — is the cornerstone of pharmacovigilance. It is essential for:

1. Early detection of risks

Individual reports of adverse reactions, especially of unexpected or severe reactions, may provide the first sign of a previously unknown problem with a medicine.

2. Improving patient safety

Once side effects are reported and analyzed, regulators and pharmaceutical companies can update safety information, adjust dosages, or issue warnings to reduce harm.

3. Supporting evidence-based decisions

Data generated from reports helps doctors and pharmacists make informed decisions about prescribing and dispensing medicines.

4. Building public trust

Active monitoring and transparent responses to safety concerns strengthen public confidence in healthcare systems and medicines.

How to report side effects?

The health ministries of most countries collaborate with international organizations like the WHO and the Uppsala Monitoring Centre (UMC) to enhance pharmacovigilance efforts. Healthcare professionals, patients, and pharmaceutical companies are encouraged to report suspected adverse drug reactions and product quality issues to the designated agencies in their respective regions.