What the label lists and what reports show
Olezarsen side effects
Olezarsen's FDA label: “Most common adverse reactions in patients with FCS (incidence >5% of TRYNGOLZA-treated patients and >3% higher frequency than placebo) were injection site reactions, decreased platelet count, and arthralgia.” FAERS holds 676 reports naming it through July 30, 2026; the reaction reported most often, leaving out the conditions it is used for, product-use terms and outcomes, is blood triglycerides increased (63 reports).
- No generic listed
Check it at the source: the olezarsen FDA label on DailyMed (effective July 3, 2026, Ionis Pharmaceuticals, Inc.); the FDA FAERS public dashboard.
What does the patient leaflet say about side effects?
From the patient leaflet: What are the possible side effects of TRYNGOLZA?Allergic reactions: TRYNGOLZA can cause side effects including allergic reactions that may be serious. Allergic reactions can include redness of the skin, red itchy bumps (hives), swelling of the face, chills or trouble breathing. Stop taking TRYNGOLZA and call your healthcare provider or get emergency help right away if you have any of these symptoms. Liver problems: TRYNGOLZA can cause increases in liver enzymes and fat stored inside the liver. Your healthcare provider may do liver tests before you start taking TRYNGOLZA or if there is an increase in your dose. […]
Source: FDA drug label, Ionis Pharmaceuticals, Inc., effective July 3, 2026 (SPL set 0f51aa8e-8475-8cf9-e063-6394a90a6848), via openFDA; the full label on DailyMed
What does the label list?
From the label: adverse reactionsMost common adverse reactions in patients with FCS (incidence >5% of TRYNGOLZA-treated patients and >3% higher frequency than placebo) were injection site reactions, decreased platelet count, and arthralgia.
From the label: adverse reactions, continuedThe following clinically significant adverse reactions are discussed elsewhere in the labeling: Hypersensitivity Reactions [ see Warnings and Precautions (5.1) ] Liver Enzyme Abnormalities [see Warnings and Precautions (5.2) ] Most common adverse reactions in patients with FCS (incidence >5% of TRYNGOLZA-treated patients and >3% higher frequency than placebo) were injection site reactions, decreased platelet count, and arthralgia. ( 6.1 ) Most common adverse reactions in patients with sHTG (incidence ≥2% higher than placebo) were injection site reactions and liver enzyme increases. ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact Ionis Pharmaceuticals, Inc. at toll free number 1-833-644-6647 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch. 6.1 Clinical Trials Experience Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of TRYNGOLZA cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice. Clinical Trial in Patients with FCS The safety of TRYNGOLZA was evaluated in 66 patients with FCS enrolled in Trial 1 (NCT #04568434) [see Clinical Studies (14.1) ]. In this trial, 43 patients received at least one dose of TRYNGOLZA, 50 mg (N=21) or 80 mg (N=22) and 23 patients received placebo. …
Source: FDA drug label, Ionis Pharmaceuticals, Inc., effective July 3, 2026 (SPL set 0f51aa8e-8475-8cf9-e063-6394a90a6848), via openFDA; the full label on DailyMed
What do FAERS reports show?
676 reports list olezarsen among the medicines taken, each a report of something that happened, not proof the medicine caused it; 3 are coded as a death and 102 as a hospital stay. Counts follow how widely a medicine is used and watched, and they are not a measure of how risky it is. Of the 22 reactions below, 1 is named by the same term (in US spelling) in the label's adverse reactions, warnings or patient leaflet; a reaction the label does not name may still be there under another word, and a report does not show that the medicine caused it.
Reports received each year
The 25 most reported reactions
Source: FDA Adverse Event Reporting System (FAERS) via openFDA, reports through July 30, 2026; reactions as MedDRA preferred terms
What next?
- Olezarsen: the full record
- label, generics, price, shortages, recalls
- Report a side effect to the FDA
- MedWatch
- Side effects hub
- the most reported medicines and reactions