What the label lists and what reports show
Tolvaptan side effects
Tolvaptan's FDA label: “Most common adverse reactions (≥5% placebo) are thirst, dry mouth, asthenia, constipation, pollakiuria or polyuria, and hyperglycemia ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact Otsuka at 1-877-726-7220 or FDA at 1-800-FDA-1088 …” FAERS holds 14,448 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 thirst (954 reports).
- Generic listed
- Boxed warning
Check it at the source: the tolvaptan FDA label on DailyMed (effective May 7, 2026, Otsuka America Pharmaceutical, 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 SAMSCA?SAMSCA can cause serious side effects including: See " What is the most important information I should know about SAMSCA? " Loss of too much body fluid (dehydration). Tell your healthcare provider if you: have vomiting or diarrhea and cannot drink normally. feel dizzy or faint. These may be symptoms that you have lost too much body fluid. Call your healthcare provider right away if you have any of these symptoms. The most common side effects of SAMSCA are: thirst dry mouth weakness constipation making large amounts of urine and urinating often increased blood sugar levels These are not all the possible side effects of SAMSCA. Talk to your healthcare provider about any side effect that bothers you or that does not go away while taking SAMSCA. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.
Source: FDA drug label, Otsuka America Pharmaceutical, Inc., effective May 7, 2026 (SPL set 5526617c-c7b9-4556-886d-729bbabbc566), via openFDA; the full label on DailyMed
What does the label list?
From the label: adverse reactionsMost common adverse reactions (≥5% placebo) are thirst, dry mouth, asthenia, constipation, pollakiuria or polyuria, and hyperglycemia ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact Otsuka at 1-877-726-7220 or FDA at 1-800-FDA-1088 ( www.fda.gov/medwatch ).
Table 1. Adverse Reactions (>2% more than placebo) in Tolvaptan-Treated Patients in Double-Blind, Placebo-Controlled Hyponatremia Trials
| System Organ Class MedDRA Preferred Term | Tolvaptan 15 mg/day to 60 mg/day (N =223) n (%) | Placebo (N =220) n (%) |
|---|---|---|
| Dry mouth | 28 (13) | 9 (4) |
| Constipation | 16 (7) | 4 (2) |
| Thirst polydipsia | 35 (16) | 11 (5) |
| Asthenia | 19 (9) | 9 (4) |
| Pyrexia | 9 (4) | 2 (1) |
| Hyperglycemia diabetes mellitus | 14 (6) | 2 (1) |
| Anorexia decreased appetite | 8 (4) | 2 (1) |
| Pollakiuria or polyuria urine output increased, micturition urgency, nocturia | 25 (11) | 7 (3) |
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, continuedMost common adverse reactions (≥5% placebo) are thirst, dry mouth, asthenia, constipation, pollakiuria or polyuria, and hyperglycemia ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact Otsuka at 1-877-726-7220 or FDA at 1-800-FDA-1088 ( www.fda.gov/medwatch ). 6.1 Clinical Trials Experience Because clinical trials are conducted under widely varying conditions, adverse reactions 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. The adverse event information from clinical trials does, however, provide a basis for identifying the adverse events that appear to be related to drug use and for approximating rates. In multiple-dose, placebo-controlled trials, 607 hyponatremic patients (serum sodium <135 mEq/L) were treated with SAMSCA. The mean age of these patients was 62 years; 70% of patients were male and 82% were Caucasian. One hundred eighty-nine (189) tolvaptan-treated patients had a serum sodium <130 mEq/L, and 52 patients had a serum sodium <125 mEq/L. Hyponatremia was attributed to cirrhosis in 17% of patients, heart failure in 68% and SIADH/other in 16%. Of these patients, 223 were treated with the recommended dose titration (15 mg titrated to 60 mg as needed to raise serum sodium). …
Source: FDA drug label, Otsuka America Pharmaceutical, Inc., effective May 7, 2026 (SPL set 5526617c-c7b9-4556-886d-729bbabbc566), via openFDA; the full label on DailyMed
What do FAERS reports show?
14,448 reports list tolvaptan among the medicines taken, each a report of something that happened, not proof the medicine caused it; 3,190 are coded as a death and 4,653 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 16 reactions below, 7 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?
- Tolvaptan: 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