What the label lists and what reports show
Betaine side effects
Betaine's FDA label: “Most common adverse reactions (> 2%) are: nausea and gastrointestinal distress, based on physician survey.” FAERS holds 1,036 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 vomiting (79 reports).
- Generic listed
Check it at the source: the betaine FDA label on DailyMed (effective April 24, 2026, Recordati Rare Diseases); the FDA FAERS public dashboard.
What does the label list?
From the label: adverse reactionsMost common adverse reactions (> 2%) are: nausea and gastrointestinal distress, based on physician survey.
From the label: adverse reactions, continuedThe following serious adverse reactions are described elsewhere in labeling: Hypermethioninemia and cerebral edema in patients with CBS deficiency [ see Warnings and Precautions ( 5.1 ) ]. Most common adverse reactions (> 2%) are: nausea and gastrointestinal distress, based on physician survey. ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact Recordati Rare Diseases Inc. at 1-888-575-8344, 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 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. The assessment of clinical adverse reactions is based on a survey study of 41 physicians, who treated a total of 111 homocystinuria patients with CYSTADANE. Adverse reactions were retrospectively recalled and were not collected systematically in this open-label, uncontrolled, physician survey. Thus, this list may not encompass all types of potential adverse reactions, reliably estimate their frequency, or establish a causal relationship to drug exposure.
Source: FDA drug label, Recordati Rare Diseases, effective April 24, 2026 (SPL set 31a684d0-cd98-4e46-b43a-ccbd17c41559), via openFDA; the full label on DailyMed
What do FAERS reports show?
1,036 reports list betaine among the medicines taken, each a report of something that happened, not proof the medicine caused it; 71 are coded as a death and 397 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 15 reactions below, 3 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?
- Betaine: 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