Acupuncture is more effective than anti-inflammatories in the treatment of period pain according to a meta-analysis of 17 randomised controlled trials. (In plain English, that means that some people have taken the trouble to have a look at 17 different respectable clinical trials and pulled all the results together to form a conclusion.) I guess, though, that some women will still prefer to just pop a pill or two to try to deal with their pain at period time, since this is quicker than going to the trouble of having some acupuncture, and maybe cheaper too if they don't have to pay for the drugs. But on the other hand anti-inflammatory medication is not free from side effects; less likely to be a problem perhaps if you only take them once a month. But then suppose you have some other aches and pains as well?
The advantage traditional acupuncture has is that, apart from being such a safe form of treatment, it looks at a woman as a whole being, and not just at her reproductive organs in isolation. In this view, period pain is maybe just the major, or one of the major, manifestations of an underlying disharmony which is not being dealt with at all by just taking a painkiller, convenient as that might be if it works. For example, consider a woman who has painful periods, who also tends to get a bit irritable running up to her period, who sometimes has migraines and who has irritable bowel syndrome. From the point of view of traditional acupuncture, all of these symptoms are part of a package, all of them are branches of the same tree, and what the woman really needs is some treatment which treats the tree as a whole, and not just one branch or another - one medication for the period pain, one for the migraines, one for the bowels etc.
In this example the root of the problem, the disharmony which underlies the various symptoms, is likely to be what is called Liver Qi Stagnation. (This could perhaps be confirmed by asking a few more judicious questions, and perhaps taking the woman's pulse.) Liver Qi Stagnation, of course, is not a term that has any meaning in the context of the form of medicine we are used to, but it has plenty of meaning within the context of the 2,000 years plus of Chinese medicine. In short, it means that things in our system are not flowing freely, transitions are not smooth; as far as the menstrual cycle is concerned, it means that the transitions from one part of the cycle to the next is not happening quite as nature intended, one consequence of which is pain. Live,r Qi Stagnation usually arises as a result of frustration, stress, even repressed anger and might be said to be the characteristic malaise of the modern woman, and the modern man as well, reflecting a way of life which involves a fairly relentless pursuit of ' success' at the expense of some of our deeper needs and nature. (What we are doing to the planet, we are also doing to ourselves.)
From this point of view, acupuncture is a way of restoring the free flow of Qi, releasing built up tension and loosening us up a little, supporting the natural cycles of our being and, in the case of the monthly cycle, promoting a smoother transition from one stage to the next. As well as thus relieving the pain at period time, it can start to open a door to a way of being in which we are more in harmony with our own bodies, with the natural world around us, and are as a result happier, freer and more content.
(Comparative efficacy and safety of NSAIDs-controlled acupuncture in the treatment of patients with primary dysmenorrhoea: a Bayesian network meta-analysis. J Int Med Res. 2018 Nov 30:300060518800609.)