Saxenda and Testosterone Interaction: What Clinicians and Patients Need to Know

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Is there a direct interaction between Saxenda and testosterone?

The Saxenda label and the Depo-Testosterone label do not list each other.

Saxenda's Drug Interactions section describes one mechanism. It delays gastric emptying and can therefore affect absorption of oral medicines, and the label advises monitoring for consequences of delayed absorption; in clinical pharmacology trials liraglutide did not change the absorption of the oral drugs tested to a clinically relevant degree [1]. Nothing in that section concerns androgens or testosterone products.

The Depo-Testosterone (testosterone cypionate injection) label names three interaction concerns. Androgens may increase sensitivity to oral anticoagulants, so the anticoagulant dose may need reducing with more frequent INR checks; concurrent oxyphenbutazone may reach higher serum levels; and in diabetic patients androgens may decrease blood glucose and therefore insulin requirements [2]. No GLP-1 receptor agonist is mentioned.

The two labels also do not contraindicate each other. Saxenda's contraindications are a personal or family history of medullary thyroid carcinoma or MEN 2, and serious hypersensitivity to liraglutide or an excipient [1]. Depo-Testosterone's are hypersensitivity, breast cancer in men, known or suspected prostate cancer, pregnancy, and serious cardiac, hepatic or renal disease [2].

Does Saxenda's gastric-emptying effect matter for testosterone?

The Saxenda label's concern is oral medicines taken with it [1]. Intramuscular testosterone esters are injected in oil and absorbed slowly from the lipid phase, which is why cypionate can be given every 2 to 4 weeks [2]. Oral testosterone also exists among approved formulations [3], but the Saxenda label does not mention testosterone.

Hematocrit and hemoglobin

Polycythemia appears among the adverse reactions listed in the Depo-Testosterone label, which also says to check hemoglobin and hematocrit periodically during long-term use and notes that increased red blood cell mass may raise the risk of thromboembolism [2].

The size of the rise depends on the formulation. A network meta-analysis of 29 placebo-controlled randomized trials covering 3,393 men found that every testosterone type raised mean hematocrit versus placebo: 4.0% with intramuscular enanthate or cypionate (95% CI 2.9 to 5.1), 3.0% with gel (1.8 to 4.3) and 1.4% with patch (0.2 to 2.6) [4]. Intramuscular enanthate or cypionate rose significantly more than patch; the other pairs were not significantly different [4]. In a retrospective review of 178 hypogonadal men followed for three years, hematocrit above 50% occurred in 66.7% of men on injectable testosterone, 35.1% on pellets and 12.8% on gels; the injection group was younger, 42.5 versus about 54 years, and started with a higher hematocrit, and the study was not randomized [5]. A separate review put the risk of erythrocytosis, defined as hematocrit above 0.52, at 315% higher than in controls [6].

Saxenda's label warnings and adverse reaction tables center on gastrointestinal effects, gallbladder disease, heart rate, kidney injury, hypoglycemia, hypersensitivity and thyroid C-cell tumors [1]. The GI numbers are high: nausea in 39.3% versus 13.8% on placebo, vomiting 15.7% versus 3.9%, diarrhea 20.9% versus 9.9% [1]. The label warns about acute kidney injury from volume depletion and says to monitor renal function in patients reporting reactions that could lead to it [1].

For context, the European Academy of Andrology treats a hematocrit above 48% to 50% as a relative contraindication to starting testosterone replacement [7].

Blood pressure and heart rate

The Depo-Testosterone label warns that testosterone can increase blood pressure, which can increase cardiovascular risk over time; it says to monitor blood pressure periodically, especially in men with hypertension, and that testosterone products are not recommended in men with uncontrolled hypertension [2]. FDA's 2025 labeling action said ambulatory blood pressure monitoring studies confirmed a blood pressure increase with all testosterone products, class-wide, and required a blood pressure warning on products that lacked one [3].

Saxenda raises resting heart rate: mean increases of 2 to 3 beats per minute versus placebo, with a change of more than 10 bpm at two consecutive visits in 34% of treated patients versus 19% on placebo, and the label says to monitor heart rate at regular intervals [1].

The cardiovascular outcome trials involved different products, which matters here. LEADER randomized 9,340 adults with type 2 diabetes and high cardiovascular risk to liraglutide, at a 1.8 mg target dose, or placebo; the composite of cardiovascular death, nonfatal MI or nonfatal stroke occurred in 13.0% versus 14.9% (hazard ratio 0.87, 95% CI 0.78 to 0.97) [8]. TRAVERSE randomized 5,246 men aged 45 to 80 with hypogonadism and existing or high risk of cardiovascular disease to 1.62% testosterone gel or placebo gel; the same composite occurred in 7.0% versus 7.3% (hazard ratio 0.96, 95% CI 0.78 to 1.17) [9]. TRAVERSE tested a gel, not an injection, and the LEADER dose is the diabetes dose rather than Saxenda's 3 mg weight-management dose. The Depo-Testosterone label still carries older wording: long-term cardiovascular safety trials have not been conducted, the studies have been inconclusive, and some but not all reported an increased risk of major adverse cardiovascular events [2].

Glucose

The Saxenda label warns that hypoglycemia can occur when it is used with insulin or an insulin secretagogue such as a sulfonylurea, and that the risk may be lowered by reducing those doses. Among adults with type 2 diabetes taking a sulfonylurea in the trial, glucose below 54 mg/dL with or without symptoms occurred in 28.2% on Saxenda versus 12.7% on placebo, with sulfonylurea doses cut 50% at the start [1].

In the other direction, the Depo-Testosterone label states that in diabetic patients the metabolic effects of androgens may decrease blood glucose and therefore insulin requirements [2].

Pregnancy

Depo-Testosterone is labeled for replacement therapy in men and is contraindicated in women who are pregnant, because testosterone can virilize a female fetus [2]. The Saxenda label says weight loss offers no benefit in pregnancy and directs that the drug be discontinued when pregnancy is recognized [1].