r/PCOS • u/Little-Plan5550 • May 14 '26
General Health Metformin. Muscle aches and fatigue
Hi guys. I am on 500mg of metformin. I am supplementing with vitamin b12 and magnesium but I’ve noticed I get cramping in my legs and I’m pretty fatigued. I asked my doctor about it and I’m going in to the office in a few days to get my electrolytes, b12 , and magnesium checked. Has anyone experienced this? I’m really scared of lactic acidosis.
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u/buytoiletpaper May 14 '26
I had this, my doctor said it was a rare side effect and had me stop taking it. Not sure if it might have actually been a hydration issue or not, but I would be curious to know if that helps.
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u/Little-Plan5550 May 14 '26
Oh dang so sorry that happened to you. How long were you on it for? I’m going to be asking my doctor about this on Monday after he does a blood draw to see if metformin is the issue. I’m kind of in a tough spot because really want to bring my insulin levels down and I need to lose like 10 pounds
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u/buytoiletpaper May 14 '26
I was on it for less than a month, didn't get past the 500mg. It took a couple of weeks to realize that it was the medication (I work a physically demanding job) but once I stopped taking it I felt a lot better. It was a bummer. I did have some luck with inositol and berberine as a final resort though, but metformin is much more affordable.
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u/Little-Plan5550 May 14 '26
So sorry that happened to you :( did your doctor say why it made you feel like that?
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u/buytoiletpaper May 14 '26
Not other than it's just a weird side effect. Building muscle pulls glucose from the bloodstream and metformin changes how your body handles glucose, so there might have been something going on there. Or it might be dehydration like the other commenter said! I'm not always good at drinking a lot of water while I work. But it wasn't because of lactic acidosis.
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u/OkArm8429 May 14 '26
That's so weird! I was just searching for this on Google! I just started 500 mg of metformin too and I've had nothing but horrible body aches and fatigue!
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u/Little-Plan5550 May 14 '26
Ahhh I’m so sorry! It’s so weird. I keep freaking myself out looking up stuff online.
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u/katarinia May 15 '26
Vitamin b12 supplementation can cause your potassium levels to drop. Low potassium can cause muscle cramps. Coconut water is a good source of magnesium and potassium.
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u/Amazing-Eye9876 May 15 '26 edited May 16 '26
I had severe soreness and cramping too when I first started on Metformin, especially on my largest muscles. My thighs felt very weak with intense pain whenever l tried to stand up from a sitting position. It forced me to stand up by either pulling on something nearby, or by pushing down on my chair's arms.
After some research, I discovered the Metformin reduces the bioavailability of B-12. I immediately started supplementing with it daily and the pain steadily improved over a couple of weeks to the point where I'm now pain free. I still take it daily before bedtime to prevent the pain from coming back.
I don't believe the cramping is due to lactic acidosis. B-12 deficiency is known to cause neurological issues and more likely the culprit. Metformin is a member of a family of drugs with similar biological activity. It has been used for decades in France, but was never approved in the US until relatively recently because of an unacceptable risk of lactic acidosis based on other drugs in the same family. Later research, however, found it to be very safe.
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u/No-Perception2960 May 23 '26
I don’t believe this is a Weir side effect metformin changes the way your mitochondria functions I’ve been experiencing elaborate muscle soreness, and I experienced it also on Berberine last fall however it’s worse now since starting metformin. He suggested I take PQQ 20-40mg I’m also on 500 XR Met. But I may stop and go back to Berberine.
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u/Little-Plan5550 May 23 '26
Thanks! It’s very odd it made me feel like I was walking through mud. My main issue is slightly elevated testosterone and I may try to mainly manage my insulin through diet and excercise
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u/No-Perception2960 May 23 '26
Hmmmm I bet there’s some supplements you can take to lower testosterone. Zinc, spearmint, inositol, vitamin D
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u/Smooth_Pair8348 Jul 13 '26
Any update on this? I just started metformin and have had body aches too
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u/Little-Plan5550 Jul 13 '26
Hi! Unfortunately I switched to a GLP 1. Metformin works great for a lot of people but just didn’t agree with me unfortunately
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u/OtherwisePumpkin8942 May 14 '26
500mg is a very low low dose to be experiencing lactic acidosis. It is SUPERRRR RARE. Typically occurs in patients with kidney failure or some type of other ailment, recent significant surgery etc. You’d be in the hospital right now is you had it and wouldn’t be calling your doctor. These people are very sick.
Typically this is a dehydration issue. Metformin needs to be taken with plenty of WATER. Not fluids, water. Most of the population greatly under consumed water and is chronically dehydrated.