Your feet tingle. Your balance isn’t what it was. You’re tired, and you keep losing your train of thought.
It’s easy to shrug and blame your age. But sometimes the culprit is a vitamin deficiency. And sometimes the reason for that deficiency is sitting in your medicine cabinet.
Two of the most widely used drugs in America can lower your vitamin B12 over time:
- Metformin: It’s the most commonly prescribed diabetes drug. Among U.S. adults treated with a single diabetes medication, metformin’s share climbed from 33% to 74% between 2003 and 2016, according to a study in Diabetes Care.
- Acid reducers: These include proton pump inhibitors like omeprazole (Prilosec) and lansoprazole (Prevacid), and H2 blockers like cimetidine. Prescription proton pump inhibitor use among U.S. adults roughly doubled from 1999 to 2018, with most of the increase among people 55 and older, according to a study in the journal Pharmacoepidemiology and Drug Safety.
How common is low B12 in older adults? Somewhere between 3% and 43% of older adults living in the community are deficient, depending on how it’s measured, according to the National Institutes of Health.
I’m a money guy, not a doctor, so talk to yours before you change anything. But here are five things worth knowing if you take either of these drugs.
1. Know whether you’re at risk
Start with metformin. In clinical trials lasting 29 weeks, about 7% of patients who began with normal B12 levels dropped below normal, according to the drug’s FDA-approved label. The label says the drop appears to reverse quickly when metformin is stopped or B12 is added.
Acid reducers work differently. Your body needs stomach acid to pull B12 out of food, and these drugs cut that acid, according to the NIH.
The FDA label for pantoprazole, another proton pump inhibitor, warns that taking acid-suppressing drugs daily for a long time, such as more than three years, may lead to poor B12 absorption.
Age adds to the risk. A stomach condition called atrophic gastritis, which also reduces B12 absorption, affects about 2% of the general population but 8% to 9% of adults 65 and older, according to the NIH.
2. Watch for symptoms that look like ‘just getting older’
Low B12 can cause anemia and nerve damage. The warning signs include:
- Numbness and tingling: Usually in the hands and feet.
- Balance problems: Feeling unsteady on your feet.
- Memory trouble: Confusion, poor memory or trouble concentrating.
- Fatigue: Feeling tired or weak.
- Other signs: Pale skin, shortness of breath, or a sore tongue or gums.
That list comes from the NIH and MedlinePlus. Notice how many of those you could chalk up to a bad night’s sleep or another birthday. That’s exactly why this gets missed.
Researchers have also looked at whether even low-normal B12 matters for the brain. See “It May Take More Than ‘Normal’ Levels of This Vitamin to Ward Off Dementia and Stroke.”
3. Ask your doctor for the right test
The basic check is a blood test for vitamin B12. Levels below 200 to 250 picograms per milliliter are generally considered low, according to the NIH.
If your number comes back borderline, ask about two follow-up tests: methylmalonic acid and homocysteine. Both tend to rise when your body is short on B12.
Doctors are being told to pay attention, too. The American Diabetes Association’s 2026 Standards of Care says doctors should consider checking B12 periodically in people on long-term metformin, especially those with anemia or nerve damage. Metformin’s label suggests checking B12 every two to three years.
Real talk — I’ve made plenty of money mistakes in my life, and I’ve spent decades helping people sidestep the ones they don’t have to make. Sign up for the free Money Talks Newsletter and let my scars save you a few of your own. Free, and worth more than that.
4. After 50, get your B12 from fortified foods or supplements
Most adults need just 2.4 micrograms of B12 a day. But the NIH says people over 50 should get most of it from fortified foods or supplements.
Here’s why. The B12 in meat, fish and dairy is attached to protein, and your stomach has to separate it. The B12 in supplements and fortified cereals is already free, so it skips that step, according to the NIH.
If you’re already deficient, treatment is usually injections, but high doses of B12 by mouth may work too.
A review of three small studies found oral doses of 1,000 to 2,000 micrograms were about as effective as shots at restoring normal levels, though the evidence was weak, according to the NIH. There’s no official upper limit for B12, because it has a low potential for toxicity.
5. Don’t quit your medicine on your own
None of this means metformin or your heartburn pill is bad for you. These drugs do important work, and stopping them can cause real problems.
The fix is usually simple: Get tested, and if you’re low, add B12. If you’ve been on an acid reducer for years, it’s also fair to ask your doctor whether you still need it.
If cost is part of what’s tempting you to cut back on a prescription, shop around first. You can compare ways to save on prescriptions in our Solutions Center.
The bottom line
If you take metformin or an acid reducer, especially for years, ask your doctor at your next visit whether you should have your B12 checked. It’s a simple blood test, and the fix, if you need one, is one of the cheapest in medicine.
And the next time your feet tingle or your memory slips, don’t just blame your birthday. Ask.
Add a Comment