Brand name · Levothyroxine sodium
Tirosint: adverse event reports filed with FDA
2,276 reports list it as a suspect or interacting product, 2010–2026. Class: l-Thyroxine.
- 2,276
- reports as suspect product
- 0% of all reports · about 143 a year
- 205
- reports, 12 months to June 2026
- 218 in the 12 months before
- 17%
- marked serious by the reporter
- 48.4% across the class
- 0.6%
- record death among outcomes, as reported
- 13 reports · not verified by FDA
Between August 2010 and June 2026, 2,276 adverse event reports received by FDA list the brand name Tirosint (levothyroxine sodium) as a suspect or interacting product. Reports that mention it only as a concomitant medication (2,084) are left out of every figure here.
In the 12 months to June 2026, 205 reports listed it, close to the 218 of the 12 months before. FDA releases FAERS data quarterly, so the newest months are incomplete and grow in later releases. Over its reporting history that is about 143 reports a year and 0% of the 20,646,523 reports in the database, and 4.4% of the reports for the l-Thyroxine class. How many people take it is not in the data, so a count is not a rate of occurrence.
Reporters most often recorded fatigue (13%), palpitations (9.4%) and feeling abnormal (8.1%). A report can list several reactions, so shares add to more than 100%; 420 different terms appear across these reports. Fatigue is recorded in 13% of these reports, about the same share as in the median l-Thyroxine drug (12.5%).
17% of the reports are marked serious by the reporter (48.4% across the class); 0.6% record death among the outcomes and 5.7% record hospitalisation, as reported. 85.8% of the reports came from consumers, and the largest patient age group is 45 to 64 (12.9%). FDA states that "a causal relationship cannot be established between product and reactions listed in a report" and that for any given report "there is no certainty that a suspected drug caused the event."
Reports by month, five years
Reports by the month FDA received them. FDA releases FAERS data quarterly, so the newest months are incomplete and grow in later releases.
By year received
2026 covers reports received through June 2026 only.
Reactions recorded in the reports
share of Tirosint reports recording the termmedian drug in l-thyroxine
- Fatiguetiredness13%295
- Palpitationsawareness of the heartbeat9.4%215
- Feeling abnormalfeeling odd or not right8.1%184
- Alopeciahair loss8%183
- Drug ineffectivethe medicine did not work as expected7.8%177
- Weight increasedweight gain7.4%169
- Malaisegeneral feeling of being unwell7.3%166
- Insomniadifficulty sleeping7.2%163
- Thyroid function test abnormal6.8%154
- Headachehead pain6.6%151
- Anxietyanxiety6.1%139
- Dizzinesslight-headedness or unsteadiness5.9%134
- Dyspnoeashortness of breath5.4%122
- Nauseafeeling sick5.4%122
- Diarrhoealoose or frequent stools4.6%104
- Product dose omission issuea dose was missed4.4%101
- Astheniaweakness or lack of energy4.3%98
- Rashskin rash4.3%98
- Product quality issuea problem with the product itself4.3%97
- Drug level above therapeutic4.2%96
- Pruritusitching4%92
- Arthralgiajoint pain3.7%85
- Weight decreasedweight loss3.5%79
- Hypersensitivityan allergic-type reaction3.4%78
- Urticariahives3.4%78
- Tremorshaking3.3%75
- Abdominal discomfortstomach discomfort3.2%73
- Heart rate increaseda fast heart rate reading3.2%72
- Painpain, site not specified3.1%71
Top 30 of 420 MedDRA preferred terms recorded across these reports, with a plain-language gloss where one is available. One report can record several terms. The hollow bar is the median share across the 6 drugs in the l-thyroxine class; it describes the reports, not the patients. FDA states that adverse event reports "represent a small percentage of total usage numbers of a product", that "common products may have a higher number of adverse events due to the higher total number of people using the product", and that the data "by themselves are not an indicator of the safety profile of the drug or biologic."
Outcomes recorded
Outcome flags as the reporter set them; a report can carry several, and "other serious" is FDA's own category for serious reports outside the named outcomes. Grey bar: all 51,210 reports in the class. FDA has not verified any outcome and states that the reports "cannot be used to estimate the incidence of these events."
Patients and reporters
Patient age
Patient sex
Who reported
Age and sex as stated in the report; the reporter's qualification is the primary source recorded by FDA. 97.1% of reports give the United States as the country of the event or reporter.
Reason for use recorded
| Indication as recorded (MedDRA) | Reports | Share |
|---|---|---|
| Hypothyroidism | 808 | 35.5% |
| Autoimmune thyroiditis | 252 | 11.1% |
| Thyroid hormone replacement therapy | 122 | 5.4% |
| Thyroidectomy | 90 | 4% |
| Thyroid disorder | 59 | 2.6% |
| Graves' disease | 12 | 0.5% |
The indication field is filled in by the reporter and is often blank; shares are of all 2,276 reports.
In context
| Measure | Tirosint | l-Thyroxine | All reports |
|---|---|---|---|
| Reports as suspect product | 2,276 | 51,210 | 20,646,523 |
| Share of that pool | — | 4.4% | 0% |
| Reports, latest 12 months | 205 | — | 1,332,454 |
| Marked serious | 17% | 48.4% | 57.4% |
| Death recorded among outcomes, per 1,000 reports | 6 | 62 | 91 |
| Hospitalisation recorded, per 1,000 reports | 57 | 172 | 213 |
| Consumer-filed share | 85.8% | 69% | 45.8% |
| Top term, share of reports | Fatigue 13% | median 12.5% | 3.7% |
Shares are of reports, not of patients treated. The number of people taking a product is not in the data, so none of these figures is a rate, and differences between columns reflect who takes a product, who reports and how long it has been sold. FDA states that adverse event reports "represent a small percentage of total usage numbers of a product", that "common products may have a higher number of adverse events due to the higher total number of people using the product", and that the data "by themselves are not an indicator of the safety profile of the drug or biologic."
Other drugs in the l-thyroxine class
| Drug | Name type | Reports | Latest 12 months | Marked serious |
|---|---|---|---|---|
| Synthroid | brand | 26,831 | 1,910 | 38.1% |
| Levothyroxine sodium | generic | 14,372 | 1,013 | 66.1% |
| Euthyrox | brand | 3,596 | 133 | 89.6% |
| Levoxyl | brand | 3,382 | 70 | 27.7% |
| NP Thyroid | brand | 753 | 30 | 66.8% |
Ordered by report count for navigation only. FDA states that adverse event reports "represent a small percentage of total usage numbers of a product", that "common products may have a higher number of adverse events due to the higher total number of people using the product", and that the data "by themselves are not an indicator of the safety profile of the drug or biologic." A brand and its generic are separate rows because reporters name them separately.
Questions about Tirosint reports
How many adverse event reports has FDA received for Tirosint?
2,276 reports list Tirosint as a suspect or interacting product in the openFDA FAERS release of 28 Sep 2026, covering reports received through June 2026. 205 of them arrived in the latest 12 months. Another 2,084 list it only as a concomitant medication.
What reactions are recorded in Tirosint reports?
fatigue (13%), palpitations (9.4%), feeling abnormal (8.1%), alopecia (8%) and drug ineffective (7.8%). These are MedDRA preferred terms coded from what the reporter described; a report can list several, and a term's presence is not a finding that Tirosint was responsible.
How serious are the reports?
17% are marked serious by the reporter. Among the outcomes recorded, 0.6% of reports include death and 5.7% include hospitalisation. FDA has not verified these outcomes and states that the reports "cannot be used to estimate the incidence" of the events.
Who files these reports?
consumer or non-health professional (85.8%), physician (7.4%) and other health professional (3.2%). Most reports reach FDA through the manufacturer, which must forward reports it receives.
Are reports for Tirosint rising?
205 reports in the 12 months to June 2026, close to the 218 of the 12 months before. FDA releases FAERS data quarterly, so the newest months are incomplete and grow in later releases. Counts also move with how many people take a product, its time on the market and publicity.
Do these reports show that Tirosint was responsible for these reactions?
No. FDA states that "a causal relationship cannot be established between product and reactions listed in a report" and that for any given report "there is no certainty that a suspected drug caused the event." The reaction may relate to the condition being treated, to other medicines, or to something else.
Is this a list of the side effects of Tirosint?
No. It is a count of what was reported to FDA. The adverse reactions observed in clinical studies are printed on the FDA-approved label, which a pharmacist or clinician can go through with you.
How do I report an adverse event?
Consumers and health professionals can report to FDA through MedWatch (Form FDA 3500 online, or 1-800-FDA-1088), or to the manufacturer, which must pass reports on. See the guide on how to report.
Where this comes from. Counts are built from the openFDA Drug Adverse Event (FAERS) bulk export released 28 Sep 2026, which holds reports FDA received through 30 Jun 2026. Drug names are as reported, resolved to the brand or generic name on the FDA label where openFDA's harmonisation matched them; classes are the pharmacologic class (EPC) from the label and the National Drug Code Directory of 17 Sep 2026. A report counts here when it lists Tirosint as a suspect or interacting product; reports listing it only as a concomitant medication (2,084) are excluded. No report narrative, lot number, patient detail or reporter identity is published. See the methodology and sources; FDA's record is authoritative, and corrections are handled within five working days.
Drug data (FAERS) through 30 Jun 2026; device data (MAUDE) through 31 Aug 2026. Not medical advice.