What the label lists and what reports show
Hydroxocobalamin side effects
Hydroxocobalamin's FDA label lists its adverse reactions in its own words. FAERS holds 4,118 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 acute kidney injury (211 reports).
- Generic listed
- In shortage
Check it at the source: the hydroxocobalamin FDA label on DailyMed (effective January 31, 2017, Actavis Pharma, 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 CYANOKIT?CYANOKIT may cause serious side effects, including: Allergic reactions. Signs and symptoms of a serious allergic reaction include chest tightness, trouble breathing, swelling, hives, itching, and rash. Seek emergency help if you experience signs and/or symptoms of an allergic reaction. Kidney problems. CYANOKIT can cause kidney problems, including kidney failure. Tell your healthcare provider if you develop crystals in your urine. Your healthcare provider will monitor your kidney function for 7 days after treatment with CYANOKIT, or longer if needed. Increased blood pressure. Increased blood pressure is a common but serious side effect during treatment with CYANOKIT. Your healthcare provider will monitor your blood pressure during treatment with CYANOKIT. The most common side effects of CYANOKIT include: red colored urine. […]
Source: FDA drug label (Cyanokit), BTG INTERNATIONAL INC., effective April 27, 2023 (SPL set d56fcc8d-bd64-46ab-b0c0-2124bd745a6b), via openFDA; the full label on DailyMed
What does the label list?
From the label: adverse reactionsMild transient diarrhea, itching, transitory exanthema, feeling of swelling of entire body, and anaphylaxis. A few patients may experience pain after injection of hydroxocobalamin. To report SUSPECTED ADVERSE EVENTS, contact Actavis at 1-800-272-5525 or FDA at 1-800-FDA-1088 or http://www.fda.gov/ for voluntary reporting of adverse reactions.
Table 3 Incidence of Adverse Reactions Occurring in >5% of Subjects in 5 g Dose Group and Corresponding Incidence in 10 g Dose Group and Placebo
This table is printed in the Cyanokit label published by BTG INTERNATIONAL INC. of April 27, 2023; the label quoted above does not print one.
| Reaction | Hydroxocobalamin N=66 n (%) | Placebo N=22 n (%) | Hydroxocobalamin N=18 n (%) | Placebo N=6 n (%) |
|---|---|---|---|---|
| Chromaturia (red colored urine) | 66 (100) | 0 | 18 (100) | 0 |
| Erythema | 62 (94) | 0 | 18 (100) | 0 |
| Oxalate crystals in urine | 40 (61) | 1 (5) | 10 (56) | 0 |
| Rash | 13 (20) | 0 | 8 (44) | 0 |
| Blood pressure increased | 12 (18) | 0 | 5 (28) | 0 |
| Nausea | 4 (6) | 1 (5) | 2 (11) | 0 |
| Headache | 4 (6) | 1 (5) | 6 (33) | 0 |
| Lymphocyte percent decreased | 5 (8) | 0 | 3 (17) | 0 |
| Infusion site reaction | 4 (6) | 0 | 7 (39) | 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.
Source: FDA drug label, Actavis Pharma, Inc., effective January 31, 2017 (SPL set a3087a39-f218-4f16-a1e7-17c39bb2eb69), via openFDA; the full label on DailyMed
What do FAERS reports show?
4,118 reports list hydroxocobalamin among the medicines taken, each a report of something that happened, not proof the medicine caused it; 311 are coded as a death and 1,636 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, 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?
- Hydroxocobalamin: 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