Ozempic, a brand of semaglutide, touches the kidneys in two directions. Its label warns of sudden kidney injury, and it also carries an approved use to protect the kidneys. How the drug works is covered in the semaglutide guide.
This page sets out both sides: when kidney injury has been reported, and what the trials measured in people whose kidneys were already damaged.
The warning: kidney injury from dehydration
Section 5.6 of the label reports “postmarketing reports of acute kidney injury, in some cases requiring hemodialysis, in patients treated with semaglutide” [1].
It says most of those events happened in people whose stomach side effects led to dehydration, “such as nausea, vomiting, or diarrhea.” Losing fluid lowers blood flow to the kidneys, which can injure them.
The label tells prescribers to monitor kidney function in people with those side effects, “especially during dosage initiation and escalation.” The fluid side of this is covered in does Ozempic cause dehydration.
How often kidney injury appeared in trials
The Wegovy label, which uses a higher dose of the same molecule for weight loss, counts the cases. Acute kidney injury occurred in 7 adults on Wegovy and 4 on placebo in the weight-reduction trials [2].
That is 0.4 and 0.2 cases per 100 patient-years. Some of these occurred alongside stomach side effects or dehydration.
The same label says the risk of kidney side effects “was increased in adult patients with a history of renal impairment,” and that they occurred more often during dose titration. Those trials included 65 people with moderate or severe kidney impairment at the start.
What a kidney injury case looks like
A 2021 case report described 2 patients with diabetic kidney disease whose kidney function worsened quickly after starting semaglutide [3]. Protein in the urine also rose.
In one patient, a kidney biopsy showed acute tubular injury on top of advanced diabetic damage. The authors wrote that long-term outcomes after this kind of injury are “not known.”
They advised caution in moderate to severe kidney disease, because of limited kidney reserve. A two-patient report shows an event can happen; it cannot say how often it happens.
The benefit: the FLOW trial
Ozempic’s label lists a third approved use: to reduce “the risk of sustained eGFR decline, end-stage kidney disease, and cardiovascular death” in adults with type 2 diabetes and chronic kidney disease [1].
That use rests on FLOW, a randomized trial of 3,533 people with type 2 diabetes and chronic kidney disease [4]. They took semaglutide 1 mg weekly or placebo, on top of standard care, for a median of 3.4 years.
eGFR is the standard estimate of how well the kidneys filter blood. Participants started with a mean eGFR of 47, and 11% were below 30, according to the label.
The main outcome combined kidney failure, a drop of at least 50% in eGFR, and death from kidney or heart causes. It occurred in 331 people on semaglutide and 410 on placebo, a hazard ratio of 0.76 (95% CI 0.66 to 0.88).
Kidney function also declined more slowly. The yearly eGFR slope was less steep by 1.16 units on semaglutide. Death from any cause was 20% lower (hazard ratio 0.80, 95% CI 0.67 to 0.95).
| Outcome | Placebo (n=1,766) | Semaglutide (n=1,767) | Hazard ratio (95% CI) |
|---|---|---|---|
| Main kidney and cardiovascular composite | 410 (23.2%) | 331 (18.7%) | 0.76 (0.66 to 0.88) |
| eGFR fell by 50% or more | 213 (12.1%) | 165 (9.3%) | 0.73 (0.59 to 0.89) |
| Chronic dialysis or transplant | 100 (5.7%) | 87 (4.9%) | 0.84 (0.63 to 1.12) |
| Cardiovascular death | 169 (9.6%) | 123 (7%) | 0.71 (0.56 to 0.89) |
| Death from any cause | 279 (15.8%) | 227 (12.8%) | 0.8 (0.67 to 0.95) |
Not every part moved on its own. The confidence interval for chronic dialysis or transplant crossed 1, and renal deaths were 5 in each group. The label says benefit “was not evident” in people already on SGLT2 inhibitors, though there were few events in that group.
People without diabetes
SELECT enrolled people with overweight or obesity and heart disease but no diabetes, and gave semaglutide 2.4 mg weekly [5]. Its prespecified kidney analysis covered 8,803 people on semaglutide and 8,801 on placebo.
The kidney composite occurred in 1.8% on semaglutide and 2.2% on placebo (hazard ratio 0.78, 95% CI 0.63 to 0.96). The authors wrote that the results “suggest a benefit” on kidney outcomes in this group.
A 2026 pooled analysis combined FLOW, SELECT and a third trial, SOUL, for 30,787 participants [6]. The kidney composite occurred in 973 people on semaglutide and 1,134 on placebo (hazard ratio 0.84, 95% CI 0.77 to 0.91).
Dosing with reduced kidney function
Section 8.6 of the Ozempic label states that no dose adjustment is recommended for kidney impairment [1]. In people with kidney impairment, including kidney failure, it saw “no clinically relevant change” in how the body handled semaglutide.
The label also says the mechanism behind the kidney benefit “has not been established.” Older adults, who more often have reduced kidney function, are covered in GLP-1 medications for seniors.
Reading the two answers together
The label holds both findings at once. Over years, in people with diabetic kidney disease, semaglutide slowed kidney decline in a large randomized trial. In the short term, dehydration from its stomach side effects has been linked to sudden kidney injury.
The trials that showed the benefit did not remove the warning. The rest of the side-effect list is in semaglutide side effects.