Low levels of vitamin D may make recovery from breast cancer surgery more painful and increase the need for opioid medications, according to research published online in the journal Regional Anesthesia & Pain Medicine.
Researchers say patients with vitamin D deficiency (below 30 nmol/L) could potentially benefit from taking supplements before undergoing a radical mastectomy.
Scientists have increasingly been studying vitamin D’s role in pain regulation. Evidence suggests the vitamin may influence how the body detects and processes pain because of its effects on inflammation and the immune system. Vitamin D deficiency is also common among people with breast cancer.
Study Explored Vitamin D and Postoperative Pain
The study was carried out at Fayoum University Hospital in Egypt between September 2024 and April 2025. Researchers followed 184 breast cancer patients scheduled for surgery to remove one breast.
Half of the participants had vitamin D deficiency (below 30 nmol/L), while the other half had vitamin D levels above 30 nmol/L. The groups were otherwise similar, with an average age of 44 in the deficient group and 42 in the sufficient group.
Patients received the hospital’s standard care before, during, and after surgery. Medical staff treating the patients did not know their vitamin D status.
During surgery, fentanyl was used to manage pain. Afterward, all patients received paracetamol intravenously every eight hours. Patients were also allowed to self-administer tramadol, another opioid pain medication, by pressing a control button.
Low Vitamin D Linked to More Pain and Opioid Use
Researchers measured pain immediately after surgery and again at 6, 12, 18, and 24 hours later. They also tracked nausea, vomiting, sedation scores, and length of hospital stay.
Patients with vitamin D deficiency were three times more likely to report moderate to severe pain during the first 24 hours after surgery compared with patients whose vitamin D levels were sufficient.
The researchers noted that none of the patients in either group reported severe pain rated 7 or higher on a 0 to 10 pain scale. The difference was entirely related to a higher rate of moderate pain levels between 4 and 6.
The vitamin D-deficient group also required more pain medication. On average, these patients received 8 μg more fentanyl during surgery, although researchers described this increase as modest.
