Flexitrinol is a highly under dosed joint pain supplement that is unlikely to do very much to help with joint pain relief. Whilst we don't have any issues with the ingredients themselves, the dosages range from 4-10X below their effective ranges for actually having a marked impact on joint pain, especially if we're looking at more severe cases as these dosages don't meet the recommendations for even mild osteoarthritis, never mind the fact that other conditions and injuries are often dosed even higher.
For example the Omega oils included in Flexitrinol come to a grand total of 90mg, whereas the studies suggest you need far more and most simple omega oil supplements offer around 1100mg (the recommended daily dosage for an adult). So, we can discount the measly 90mg here and look at the rest of the ingredients which suffer from similar problems. It's significantly overpriced for what it is costing almost $100 for a months supply and all in all we cannot recommend Flexitrinol.There are much better and correctly dosed joint supplements available for less than this. We would recommend that you take a look at our best joint pain supplement list here.
There are limited customer flexitrinol reviews that look to be legitimate available online, although the majority seem to either complain about the product not doing anything, (which based on the dosages is what we'd expect) or complaining about only getting a 15 day supply for a $100 price tag. On Amazon they currently sit at a middling 3* rating, although a lot of 3* ratings say it simply didn't work, and there's normally a couple of fake ones on Amazon upping the overall ratings.
The most commonly asked questions we found when researching our flexitrinol review
There can be side effects from the individual ingredients in flexitrinol, however because it doesn't actually contain enough of the ingredients to effectively improve joint health, it's unlikely that you'll experience any. In a realistic worst case scenario, assuming you have no allergies, you could experience some mild heart palpitations and rise in blood pressure as a result of glucosamine hcl's potential side effects.
Glucosamine HCL is a good ingredient, unfortunately it's under dosed in flexitrinol to be effective for joint pain relief with studies showing that it should be dosed at 1500mg (or 500mg three times per day).  Unfortunately this being 3 times more than the Flexitrinol dose is actually the best that we're going to see. It's actually good enough to be available on prescription in some countries for osteoarthritis , but in the higher dosages that we mentioned. There is some potential minor benefits for taking 500mg, but considering that this is the best the joint health supplement has to offer, we're not rating this highly.
MSM seems to work quite well for joint pain, but it also looks like it needs to be used in dosages of 3 grams plus , this is 100X more than the total of the 2 ingredient proprietary blend of MSM and chondroitin that we have here. It has also been shown to improve joint mobility, and is generally considered a good supplement. Unfortunately, due to the large volumes of it required to be effective, a lot of supplements include it in to low of an amount to be effective, for joint support. It is generally not a good ingredient for a combined joint supplement and quite often it's added in just to have another ingredient on the product label.
Chondroitin Sulfate is like the rest of the ingredients we've looked at in our flexitrinol review, completely under dosed, whilst we can't say exactly how bad it is, dosages of chondroitin sulfate are also substantially higher to reduce joint pain.
Omega 3 fatty acids are essential for joint health. They've been proven to work to reduce joint pain in multiple studies and clinical trials to generally positive results, even in relatively severe cases resulting in reduced need for pain relief. However, Flexitrinol don't give you enough of them and they are guilty of a common supplement trend of misleading proprietary blends. All of Flexitrinol's talk about the proprietary omega blends are just their for marketing purposes. There are different types of omega fatty acids, with EPA and DHA, being the two that matter for joints. There are also different amounts of these in different Omega sources. This much is true. However, what Flexitrinol and a lot of other supplements don't tell you, is that this really doesn't make all that much difference. This is because the sources that contain more are actually harder for your body to break down, and you simply don't absorb as much, so it functionally balances out in real terms. The only exception to this is in some algae's which only contain one of the acids.
Boron is typically dosed at 10mg not 1mg. We're really not sure why they've gone so low here, it's not even a particularly expensive ingredient. 1mg won't be effective for anything. That said Boron is an effective anti inflammatory so had it been dosed correctly we'd have said it was a good inclusion.
Flexitrinol simply doesn't have enough of the active ingredients for us to consider it a good joint health supplement, there are far better correctly dosed products that promote joint health that are available at the same price point. The product doesn't seem to have anything really going for it when we compare it to anything that's on our best joint health supplements list. The ingredients are all good choices. Albeit sometimes the cheaper options. Flexitrinol seems like a cash grab, rather than an attempt to action make a good joint mobility aid.
1 - https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2686334/
2 - https://bnf.nice.org.uk/drugs/glucosamine/
3 - https://pubmed.ncbi.nlm.nih.gov/16309928/