What the label lists and what reports show
Mitapivat side effects
Mitapivat's FDA label: “The most common adverse reactions including laboratory abnormalities (≥ 10%) in patients with PK deficiency were estrone decreased (males), increased urate, back pain, estradiol decreased (males), and arthralgia.” FAERS holds 1,017 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 haemoglobin decreased (211 reports).
- No generic listed
Check it at the source: the mitapivat FDA label on DailyMed (effective June 30, 2026, Agios 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 PYRUKYND?PYRUKYND may cause serious side effects, including: Rapid breakdown of red blood cells (acute hemolysis) has happened after suddenly interrupting or stopping treatment with PYRUKYND. You should not suddenly stop taking PYRUKYND. If you have to stop your treatment with PYRUKYND, your healthcare provider should monitor you closely. Tell your healthcare provider right away if you develop any signs or symptoms of breakdown of red blood cells including: yellowing of your skin or the whites of your eyes (jaundice) dark colored urine dizziness feeling tired shortness of breath confusion Liver injury has happened in people with another condition during the first 6 months of treatment with mitapivat when given at a dose higher than recommended for people with PK deficiency. […]
Source: FDA drug label, Agios Pharmaceuticals, Inc., effective June 30, 2026 (SPL set 4ccee896-e313-4c6c-9674-b4746ada0a90), via openFDA; the full label on DailyMed
What does the label list?
From the label: adverse reactionsThe most common adverse reactions including laboratory abnormalities (≥ 10%) in patients with PK deficiency were estrone decreased (males), increased urate, back pain, estradiol decreased (males), and arthralgia.
Table 3: Adverse Reactions (≥ 5%) in Patients Receiving PYRUKYND in ACTIVATE
| Adverse Reaction | All Grades (%) | Grade ≥3 (%) | All Grades (%) | Grade ≥3 (%) |
|---|---|---|---|---|
| Back pain a | 15% | 0 | 8% | 0 |
| Arthralgia b | 10% | 0 | 5% | 0 |
| Hypertriglyceridemia c | 8% | 5% | 3% | 0 |
| Gastroenteritis | 8% | 3% | 0 | 0 |
| Hot flush d | 8% | 0 | 0 | 0 |
| Oropharyngeal pain | 8% | 0 | 5% | 0 |
| Hypertension | 5% | 5% | 0 | 0 |
| Arrhythmia e | 5% | 0 | 0 | 0 |
| Breast discomfort | 5% | 0 | 0 | 0 |
| Constipation | 5% | 0 | 0 | 0 |
| Dry mouth f | 5% | 0 | 0 | 0 |
| Paresthesia | 5% | 0 | 0 | 0 |
Rows and numbers as the label prints them, under its own column headings (the first rows of a longer table where it runs on). A reaction in a trial table is not necessarily caused by the medicine, and trials differ from everyday use.
From the label: adverse reactions, continuedThe following clinically significant adverse reaction is described elsewhere in labeling: Acute Hemolysis with Abrupt Treatment Discontinuation [see Warn ings and Preca utions (5.1) ]. Hepatocellular Injury in Another Condition [see Warnings and Precautions (5.2) ]. The most common adverse reactions including laboratory abnormalities (≥ 10%) in patients with PK deficiency were estrone decreased (males), increased urate, back pain, estradiol decreased (males), and arthralgia. ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact Agios Pharmaceuticals at 1-833-228-8474 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch. 6.1 Clinical Trial Experience Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice. A total of 155 patients received PYRUKYND, 79% of whom were exposed for longer than 24 weeks. PYRUKYND was administered up to 50 mg orally twice daily in 67 patients with PK deficiency in the ACTIVATE trial (N=40) and the ACTIVATE-T trial (N=27) [see Clinical Studies (14) ]. ACTIVATE Trial In the ACTIVATE trial patients with PK deficiency who were not regularly transfused received PYRUKYND in incremental doses up to 50 mg twice daily (N=40) or placebo (N=39). …
Source: FDA drug label, Agios Pharmaceuticals, Inc., effective June 30, 2026 (SPL set 4ccee896-e313-4c6c-9674-b4746ada0a90), via openFDA; the full label on DailyMed
What do FAERS reports show?
1,017 reports list mitapivat among the medicines taken, each a report of something that happened, not proof the medicine caused it; 6 are coded as a death and 90 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 20 reactions below, 4 are 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?
- Mitapivat: 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