Does slippery elm raise blood pressure? What the research does and doesn't show

The evidence doesn't support slippery elm bark (Ulmus rubra) affecting blood pressure in either direction — no published research has tested it. If you've seen a connection between "elm bark" and blood pressure, it likely traces to one of two things: a different, unrelated ingredient sometimes combined with slippery elm bark in multi-herb formulas, or studies of a completely different elm species.

What the evidence doesn't support

It doesn't support slippery elm bark raising blood pressure. It doesn't support slippery elm bark lowering blood pressure either. No published human or animal study has tested Ulmus rubra bark itself against blood pressure in any direction — this is an absence of research, not a tested negative result.

What the trials found

The closest thing to relevant research is indirect. The only human study to use slippery elm bark in a diagnosed sample was a 2010 pilot study of 31 adults with irritable bowel syndrome, split into two open-label, uncontrolled formula arms. One of those formulas combined slippery elm bark with lactulose, oat bran and licorice root — and licorice, separately, has documented effects on blood pressure. A 2024 meta-analysis of 8 randomized controlled trials in 541 people found that licorice products dominated by glycyrrhizic acid raised both systolic blood pressure (by about 3.5 mmHg on average) and diastolic blood pressure (by about 1.3 mmHg), while licorice products dominated by flavonoids instead did not. That finding is about licorice, not slippery elm, and the 2010 pilot study didn't measure blood pressure at all — but it's a plausible, documented reason someone taking a slippery-elm-and-licorice formula might have a real blood-pressure question worth asking about the licorice, not the slippery elm.

Separately, a search for "elm bark and blood pressure" can also surface research on Ulmus macrocarpa, a different elm species from the Ulmus rubra used in slippery elm supplements. A rat study of Ulmus macrocarpa root bark extract found it relaxed isolated blood vessels and lowered blood pressure in hypertensive rats over 42 days of dosing. That's a different plant, tested only in animals, and it says nothing about Ulmus rubra bark or about people.

Questions people ask

Does slippery elm raise blood pressure?

No published research supports this. No study has tested slippery elm bark (Ulmus rubra) against blood pressure at all. If you're taking a multi-herb product that lists slippery elm bark, check the full ingredient list — licorice root, a separate and common co-ingredient, is documented to raise blood pressure in some people, and that's a more likely explanation for a blood-pressure concern than slippery elm itself.

Does slippery elm bark tea raise blood pressure?

No study has tested slippery elm tea, or slippery elm in any form, against blood pressure. The same caveat applies: check whether a commercial tea blend adds licorice root or another ingredient with its own documented blood-pressure effect.

Can slippery elm bark raise blood pressure?

No published research connects slippery elm bark itself to a blood-pressure change in either direction.

When to talk to a doctor

If you have high blood pressure or take blood pressure medication, check any slippery elm product's full ingredient list for licorice root or other added botanicals before assuming slippery elm bark alone is the only thing in it, and ask a doctor before adding any new supplement. Slippery elm is not a treatment for high or low blood pressure, and nothing above supports using it as a substitute for monitoring or medical care.

Related reading: slippery elm and medications: what to check, who should not take slippery elm, and slippery elm benefits: what the research does and doesn't show.