4 Findings About Vitamin K Injections for Period Pain

A Chinese trial found greater one-hour pain relief

In the 2016 Shanghai trial¹, 82 women were randomized and 80 completed follow-up. They were 14–25 with severe primary period pain. Treatments compared K3 at SP6, an acupuncture point; saline there; and K3 by another injection regimen.¹

At 60 minutes, pain was about 1.5, 3.0 and 3.3 out of 10, respectively, versus around 8 initially. K3 at SP6 performed significantly better.¹

Six-month improvement did not establish a lasting advantage

Longer-term pain-intensity and duration measures did not differ significantly between groups. All improved across six follow-up cycles, but there was no untreated group and rescue pain medicines were allowed.¹

The U.S. pilot used K1 and was much smaller

The 2014 U.S. crossover pilot randomized 15 women; 14 completed. Participants received K1 at SP6 and saline at a different point, in randomized order with at least two months between treatments.²

Pain fell by 2.5 points after K1 versus 1.8 after saline at one hour. The authors described the comparison as a trend, reporting P < 0.10, rather than a firm demonstration of superiority. Because both the injected substance and location changed, this design could not isolate the contribution of each.²

K3 injections are not evidence for a supplement bottle

NIH distinguishes K1 and K2, used in dietary supplements, from menadione, or K3. It reports that K3 damaged liver cells in laboratory studies and is no longer used in dietary supplements or fortified foods.³

These findings do not establish that oral K1 or K2 treats cramps.¹²

Keep the pain-assessment appointment

NHS⁴ guidance recommends assessment when pain disrupts daily activities or periods become more painful, heavier or irregular. Severe or worse-than-usual pain that has not responded to painkillers needs urgent advice. Outside the UK, use your local urgent-care service.⁴

“The Pain Kit” in Period, Handled pairs a pain score with what you tried and what the pain stopped you doing. Bring that dated record to discuss established options and whether the cause needs further investigation.