Women with low vitamin D levels may have a more painful recovery after breast cancer surgery and may require significantly more opioid drugs afterwards, according to research published in the online journal Local anesthesia and pain treatment.
The results of this study suggest that breast cancer patients with vitamin D deficiency (<30 nmol/L) may benefit from taking vitamin D supplements before undergoing radical mastectomy.
Researchers say there is growing evidence that vitamin D plays an important role in how the body senses and regulates pain. Scientists believe this may be related to the vitamin’s anti-inflammatory properties and effects on the immune system. Vitamin D deficiency is also common in breast cancer patients.
A study investigating pain after breast cancer surgery
To explore this link, researchers conducted a prospective observational study at Egypt’s Fayoum University Hospital from September 2024 to April 2025.
The study involved 184 women with breast cancer who were preparing for surgery to remove one breast. Half of the participants had vitamin D deficiency (<30 nmol/L), while the other half had vitamin D levels above 30 nmol/L. The two groups were otherwise similar, with mean ages of 44 and 42 years.
Doctors and nurses caring for the patient were unaware of the patient’s vitamin D status. All participants received standard hospital care before, during, and after surgery.
During the surgery, the patient was given fentanyl to control acute pain. After surgery, all patients received intravenous paracetamol every 8 hours. Patients could also self-administer tramadol, another opioid analgesic, by pressing a control button.
Patients with low vitamin D required more opioids
Pain levels were recorded immediately after surgery and at 6, 12, 18, and 24 hours. Researchers also tracked nausea, vomiting, sedation levels, and length of hospital stay.
Patients with vitamin D deficiency were three times more likely to experience moderate to severe pain in the first 24 hours after surgery than those with sufficient vitamin D levels.
The researchers noted that no patients in either group reported severe pain of 7 or higher on a standard 0 to 10 pain scale. This difference was entirely related to the greater number of patients experiencing moderate pain levels between 4 and 6.
The vitamin D-deficient group required more opioid drugs. On average, these patients received more than 8 micrograms of fentanyl during surgery, which the researchers described as a small increase.
However, after surgery, the difference became even greater. Patients with low vitamin D used an average of 112 mg more tramadol than patients with sufficient vitamin D levels. Medication was patient controlled and the upper dose limit was 50 mg per hour.
Complications of vitamin D and recovery
Opioid drugs can cause side effects such as nausea, vomiting, drowsiness, and confusion. It also carries the risk of dependence and dependence.
The study found that postoperative nausea occurred more frequently in patients with vitamin D deficiency. Vomiting was only reported in the deficiency group, but the researchers said the difference was too small to be considered statistically significant.
The researchers acknowledged some limitations. Because this study was observational and conducted at a single medical center, it cannot prove that vitamin D deficiency directly caused increased pain. The research team also did not measure inflammatory markers that may explain how vitamin D affects pain. Additionally, information on preoperative anxiety, depression, cancer stage, previous treatments, and sleep problems was not collected.
Despite these limitations, the researchers concluded that “vitamin D deficiency is associated with an increased incidence of moderate to severe postoperative pain and increased opioid intake in patients undergoing unilateral radical mastectomy.”
The researchers added, “Preoperative vitamin D supplementation in breast cancer patients with vitamin D levels <30 nmol/L may play a role in modulating postoperative pain."
