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Milk Thistle Side Effects

Jessica Drew
A milk thistle flower

Milk thistle side effects are uncommon but can range from mild to quite severe. This herb has been around since Greco-Roman times. Milk thistle comes with a long list of benefits and has been used to help cure a variety of ailments. Just some of the traditional uses of milk thistle include correcting liver dysfunction, detoxifying the body and treatment for cirrhosis. The modern medical community even affirms many of the ways the herb is used to treat certain illnesses. There is no equivalent pharmaceutical drug.

Like all herbs, milk thistle has not been tested or approved for safety by the FDA, and it must be consumed with caution. The good news is that over the thousands of years this herb has been consumed by humans, side effects appear to be rare. However, the not so good news is that you have no way of knowing if you will experience side effects from taking this herb before you try it. The best course of action is to understand the side effects and interactions, and to consult with your doctor before taking the herb.

Milk Thistle Side Effects

Mild Side Effects

There have only been a few clinical studies on milk thistle side effects and the studies have largely found that the side effects of this herb are hard to come by and very mild when they do arise. However, the mild side effects of the herb do encompass a wide range of issues that include:

  • Nausea
  • Diarrhea
  • Indigestion or heartburn
  • Gas and bloating
  • Loss of appetite
  • Headaches
  • General weakness
  • Insomnia
  • Joint pain
  • Irritated eyes and runny or stuffy nose
  • Impotence

There is also a danger of unknown side effects occurring from contaminated milk thistle. Herbs are not as strictly regulated as prescription or non-prescription drugs. Because of this, there have been past incidents where milk thistle products were found to contain significant amounts of other herbs, medications or even heavy metals. Purchasing only high quality products from trusted manufacturers can minimize this chance.

Consult a doctor to find out more about side effects

Moderate to Severe Side Effects

Moderate to severe side effects from milk thistle are extremely rare and mainly occur in the form of an allergic reaction. A severe allergic reaction to this herb can cause anaphylaxis, a life-threatening condition that causes throat tightness, shortness of breath, and possibly a loss of consciousness. Unfortunately, there is no way of knowing if you're allergic to milk thistle before you try it, so the best thing to do if you think you're having an adverse reaction to the herb is to watch out for any symptoms. Symptoms of an allergic reaction to the herb can include:

  • Itching
  • Rash or hives
  • Swelling of the throat and mouth
  • Wheezing and difficulty breathing

If you experience any of these symptoms after taking milk thistle, seek immediate medical attention.

Possible Interactions with Medications

Milk thistle does interact with medications as it protects the liver from several drugs that typically degrade liver function. Therefore, if you're taking any medications, you should check with your doctor before taking milk thistle. Some known medications that interact with the herb include the following.

  • Antipsychotics

This group of medications refers to drugs that treat schizophrenia and includes butyrophenones (such as haloperidol) and phenothiazines (such as chlorpromazine, fluphenazine, and promethazine). Milk thistle protects the liver against damage from these drugs.

  • Aspirin

It has been hypothesized that the herb will increase the effectiveness of aspirin in persons with liver cirrhosis.

  • Chemotherapy Medications

More research is needed but preliminary findings suggest that the herb may protect the kidneys from the toxic side effects associated with cisplatin and cyclosporine, two medications that are often used to treat cancer. However, the anticancer effect of cisplatin diminished with the consumption of milk thistle.

Pregnant and Breastfeeding Mothers

Many product manufacturers and distributors warn pregnant and breastfeeding mothers against taking milk thistle. The effect the herb has on an unborn baby is unknown and therefore pregnant women should avoid it. However, nursing mothers with low milk supplies have used the herb for centuries to increase the flow and volume of their milk. If you're a nursing mother considering taking the herb, be sure to check with your doctor first.

Overall, milk thistle has many benefits that outweigh the small potential risk of side effects. The most important measure to take before consuming the herb is to check with your doctor and let him or her know of any medications you are taking. Then carefully monitor and report any symptoms you experience.

Milk Thistle Side Effects