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Cramp bark (Viburnum opulus) — also known as guelder rose, highbush cranberry, and snowball tree — is a tall, flowering shrub with red berries and clusters of white flowers.

Native to Europe, it also grows well in the United States and Canada.

An herbal supplement made from the shrub’s dried bark has traditionally been used to treat pain from muscle cramps, especially period cramps, although other parts of the plant may also offer benefits.

The supplement shows promising potential to relieve pain and promote healthy kidney function, and emerging research suggests that it may offer many other benefits as well.

This article takes a close look at cramp bark, including its uses, potential benefits, and how to take supplements containing it.

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Cramp bark is used in alternative medicine for various purposes.

It’s claimed to help relieve pain from cramps, and some recent research indicates it may help prevent kidney stones (1, 2).

Furthermore, some people take cramp bark supplements to alleviate other symptoms of premenstrual syndrome (PMS), as well as to help treat insomnia, anxiety, and cancer (3, 4, 5).

Although the berries and flowers are not usually included in cramp bark supplements, they may offer other health benefits, including constipation relief (3).

Nevertheless, evidence supporting these effects is limited.

May help relieve pain from cramping

Cramp bark’s name comes from its use as a pain treatment for cramps, particularly menstrual cramps.

Some research indicates that cramp bark fruit extracts help relax muscles and blood vessels, which can relieve pain and reduce blood pressure. Other herbal supplements from the Viburnum family, such as black haw, may exert similar effects (6, 7).

Still, despite its long history as a treatment for cramps, there is little scientific evidence to support this claim (6).

Some people also use cramp bark to treat symptoms of premenstrual syndrome (PMS).

One study found that an herbal supplement containing cramp bark, among other ingredients, helped reduce symptoms of PMS. However, more research is needed to understand if cramp bark itself is effective for this use (4).

May promote healthy kidney function

Cramp bark may help prevent kidney stones.

Some people can develop kidney stones due to a lack of citrate in their urine. Healthcare providers often recommend that these people consume a kidney stone diet. This includes foods high in citrate, such as lemons and limes.

Cramp bark fruit is also high in citrate, which makes it a viable alternative for people who develop kidney stones (1).

In one study in 103 people with small kidney stones, those who took cramp bark extract alongside the medication diclofenac excreted more kidney stones in a shorter period than those who only took diclofenac (2).

Those who took cramp bark also needed fewer additional treatments to remove their kidney stones and required less pain medication (2).

However, more research is needed to investigate cramp bark’s effects on kidney stones.

Other benefits

Cramp bark is high in flavonoids and carotenoids — two antioxidants that can help prevent and reverse cellular damage in your body (8, 9).

They may also help reduce your risk of developing type 2 diabetes. In fact, these antioxidants have been found to have antidiabetic effects in animal and test-tube studies (9, 10).

One study in rats found that the antioxidants in cramp bark may help treat endometriosis, a disease that affects the female reproductive system (11).

Researchers are also using cramp bark alongside materials like copper and silver to make microscopic nanostructures with antibacterial and anti-inflammatory properties (12, 13).

Although the test-tube and animal research on these nanostructures is in its early stages, they could be used to develop new medications or medical devices (12, 13).

In addition, cramp bark is commonly used in alternative medicine to treat insomnia and anxiety. However, research on these benefits is extremely limited (3).

Finally, researchers have also found that cramp bark juice slowed the growth of tumors in rats (5).

Nevertheless, since this evidence is limited to animal and test-tube studies. Further research in humans is needed to fully understand the effects of cramp bark in this regard.

summary

Cramp bark may help relieve pain from cramping, reduce PMS symptoms, and prevent kidney stones. However, much more research in humans is needed before cramp bark can be recommended for these applications.

No side effects or adverse events related to cramp bark supplements have been reported.

However, if you are pregnant or nursing, you should consult your healthcare provider before using cramp bark.

Also, be aware that raw cramp bark berries, although edible, are considered mildly toxic and may cause digestive upset if consumed in large amounts (14).

summary

Cramp bark supplements have no reported side effects, but if you are pregnant or nursing, consult your healthcare provider before using them. Raw cramp bark berries are considered edible but can cause digestive upset.

Cramp bark supplements are most commonly available as tea or concentrated liquid extracts. However, you can also purchase them in capsule form.

Some cramp bark supplements — especially those formulated for menstrual cramps or PMS — may also contain other herbs, such as valerian root or ginger (15, 16).

Most cramp bark supplements are made only from the bark of the plant, but some also include the flowers or berries.

Because supplements are not regulated by any governing body, you should only purchase products that have been tested and approved by a third-party organization, such as United States Pharmacopeia (USP) or ConsumerLab.

summary

Cramp bark supplements are usually made from the bark of the plant. They can be purchased in tea, liquid extract, or capsule form.

Cramp bark has been widely used in alternative medicine to help treat cramping pains, especially those from menstrual cramps.

Some research suggests it may also help prevent kidney stones and type 2 diabetes.

However, this research is limited, and most of it has been conducted in test tubes or on animals.

While the initial research results on cramp bark supplements appear promising, more studies are needed to fully understand their benefits.

If you would like to try cramp bark, speak with your healthcare provider before purchasing it locally or online.