Adverse reaction reports in Portugal rise with GLP-1 use

Portugal’s regulator Infarmed has received 266 suspected adverse reaction reports this year for weight-loss and diabetes drugs, roughly one per day. Between 1 January 2024 and 21 September 2026, the national pharmacovigilance system logged 695 adverse reaction reports in Portugal for four GLP-1 receptor agonists, according to data Infarmed gave to Lusa.

Adverse reaction reports in Portugal by drug

Reported symptoms include vomiting, diarrhoea and hair loss. Tirzepatide, the active substance in Mounjaro, accounts for most reports: six in 2024, 295 in 2025 and 186 up to 21 September 2026. Mounjaro reached the Portuguese market on 1 November 2024 and is the only obesity medicine sold in Portugal that can also be used to control diabetes. Semaglutide (Ozempic and Rybelsus) recorded 12 reports in 2024, 46 in 2025 and 54 in 2026. Dulaglutide (Trulicity) recorded 12, 21 and 21, while liraglutide (Victoza and Saxenda) fell from 31 in 2024 to six in 2025 and five so far this year.

Use has grown alongside reports

Tirzepatide packs dispensed in community pharmacies in mainland Portugal rose from 10,689 in 2024 to 434,768 in 2025, and reached 395,369 by June 2026. Semaglutide packs went from 399,420 in 2024 to 626,142 in 2025 and 485,424 in the first half of 2026. Infarmed says its reporting rate has stayed stable, with small swings that weigh most heavily on liraglutide because it has the least exposure.

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Why it matters: these are counts of suspected reactions, not a rate of harm. The source gives no per-patient denominator, so it cannot show how often these drugs cause a reaction. Pack volumes rose sharply over the same years, which is the context the rising counts sit in. Sweden has reported a similar rise for semaglutide, so the trend is not confined to Portugal.

Source: Público, reporting Lusa, 15 October 2026.