Is It Safe to Take Herbal Supplements Long Term? Liver, Interactions and Cycling

Short answer: For most healthy adults, taking a well-made herbal supplement at the label dose for months is usually low risk, but “long term” is exactly where the evidence gets thin: most herbs have only been studied for weeks to a few months. The three real long-term risks are liver injury (rare but serious), interactions with prescription drugs, and poor product quality. The safest approach is to take the lowest effective dose, keep your doctor and pharmacist informed, review whether you still need each product once a year, and stop at once if you notice warning signs such as yellow eyes or dark urine.

Key Takeaways

• Most herbal studies are short. For Asian ginseng, NCCIH says use by mouth for up to 6 months appears safe for most people, but questions remain about longer use.^[2]
• In a U.S. liver injury registry, herbal and dietary supplements were blamed for 16% of 845 drug or supplement liver injury cases, rising from 7% in 2004 to 2005 to 20% in 2010 to 2012.^[4]
• Mislabeling is common in the products behind those cases: only 90 of 203 labeled supplements matched their label when chemically tested.^[5]
• Interactions matter more than “toxicity” for men on medication. St. John’s wort, goldenseal, ginkgo and ginseng all have documented or suspected drug interactions.^[1]
• There is little research on fixed “cycling” schedules, but a planned break is a practical way to check whether a product is still doing anything for you.

Why “long term” is the gap in herbal research

When people ask whether it is safe to take herbal supplements long term, they usually assume someone has tested a herb for years. In most cases, nobody has. Clinical trials of botanicals typically run for weeks or a few months, because longer trials are expensive and few supplement ingredients have a sponsor willing to pay for them. That leaves three types of evidence for long-term use:

• Short human trials, which can show a herb is well tolerated for the length of the study but say little about year three or year five.
• Traditional use, which suggests a plant is not acutely poisonous at food-like amounts, but traditional preparations are often very different from modern concentrated extracts.
• Safety surveillance, meaning case reports and registries that collect harm after it happens. This is how most long-term problems (especially liver injury) are discovered.

The NIH Office of Dietary Supplements puts the core point simply: the term natural “doesn’t always mean safe,” and some botanicals, such as comfrey and kava, can harm the liver.^[3] Supplements also do not need FDA approval before they are sold, so the safety evidence a company holds is not reviewed by the agency before the product reaches shelves.^[3] For more on what that means in practice, see our guide to whether supplements are FDA approved.

Risk 1: herbal supplements and liver damage

The liver processes most of what you swallow, which makes it the organ most exposed to concentrated plant compounds. Liver injury from herbs is uncommon, but it is the main serious harm doctors see, and it has been growing.

What the registry data show

The U.S. Drug-Induced Liver Injury Network (DILIN) tracks confirmed cases of liver damage caused by drugs and supplements. In data presented in 2013, 136 of 845 cases (16%) were attributed to herbal and dietary supplements, and the supplement share climbed from 7% in 2004 to 2005 to 20% in 2010 to 2012.^[4] Bodybuilding products were the single most common cause. Non-bodybuilding supplement cases were more severe in one key way: 13% required a liver transplant, compared with 3% of prescription drug cases.^[4]

The trend continued. A 2022 study in the journal Liver Transplantation, as reported by Straight Arrow News, found that the share of patients added to the U.S. liver transplant waiting list because of supplement-related liver failure rose from 2.9% in 1995 to 24.1% in 2020.^[6] A University of Michigan analysis cited in the same report estimated that about 15 million Americans take at least one of six botanicals linked to liver toxicity: turmeric, green tea extract, ashwagandha, garcinia cambogia, red yeast rice and black cohosh.^[6]

Supplements that cause liver damage most often

The NIH LiverTox database, run by the National Institute of Diabetes and Digestive and Kidney Diseases, keeps individual safety records for herbs and supplements including ashwagandha, kava, green tea, ginseng, garcinia cambogia and androgenic steroids.^[7] Having an entry does not mean a herb is dangerous for everyone; it means liver injury has been reported often enough to document. The table below summarizes the patterns from the sources we reviewed.

Warning signs of liver trouble

In the DILIN cases, jaundice (yellow skin or eyes) and itching were very common.^[4] Stop the supplement and get medical care promptly if you notice yellowing of the skin or eyes, dark urine, pale stools, persistent itching, pain in the upper right abdomen, nausea or unusual fatigue. Bring the bottle with you: doctors often need the exact product and lot to work out the cause.

Risk 2: interactions with your medications

For men who take prescription drugs, interactions are usually a bigger long-term issue than direct toxicity. Many herbs change how the liver and gut handle medicines, mainly through cytochrome P450 enzymes and a transporter called P-glycoprotein. NCCIH notes that most identified interactions come from animal, cell or indirect studies, and that good clinical studies are limited, but some are well documented in humans.^[1]

• St. John’s wort is a potent inducer of both P450 enzymes and P-glycoprotein. It has clinically significant interactions with cyclosporine, indinavir, warfarin, digoxin, benzodiazepines and oral contraceptives.^[1]
• Goldenseal lowered metformin levels by about 25 percent in healthy adults in an NCCIH-funded study, which could affect blood sugar control.^[1]
• Ginkgo taken with warfarin is associated with a higher risk of major bleeding than warfarin alone.^[1]
• Asian ginseng may lower blood sugar and interfere with blood clotting, and possible interactions with blood pressure drugs, statins and some antidepressants are uncertain.^[1][2]
• Green tea extract may reduce levels of atorvastatin, and high amounts of green tea may lower nadolol levels.^[1]

NCCIH advises extra caution with drugs that have a narrow margin between a helpful and a harmful dose, such as warfarin, digoxin and chemotherapy.^[1] The ODS also reminds people to mention every supplement before surgery, because some can increase bleeding or change the response to anesthesia.^[3]

Risk 3: product quality over months and years

A quality problem that hardly matters in a one-week trial adds up over a year of daily use. In the DILIN analysis of products collected from 1,268 patients, only 90 of 203 labeled products matched their chemical contents, meaning more than half did not contain what the label said.^[5] Switching brands often makes this worse, because every new product is a new unknown.

Independent testers such as NSF International and U.S. Pharmacopeia check products, and passing products may carry a seal. The ODS is clear that these seals confirm quality, not that a product is safe or effective.^[3] Our guides on third-party tested supplements and dangerous supplement ingredients explain what to look for.

Should you cycle supplements?

Cycling means planned breaks, for example several weeks on and a week or two off. It is popular in fitness circles, but for most herbs there are no trials comparing cycled and continuous use, so any fixed schedule you see online is opinion, not evidence. That said, a break has practical value:

• It tests whether the product still helps. If you notice no difference after two or three weeks off, you may not need it.
• It respects the limits of the data. When a herb, like Asian ginseng, has reassuring data only up to about 6 months, a periodic review is reasonable.^[2]
• It makes side effects easier to spot. If sleep, digestion or blood pressure improve during a break, that is useful information for your doctor.

Always follow the label and your clinician’s advice first. If you stop a herb taken alongside a medication, tell your doctor, because stopping can change drug levels too. For a framework on judging results, see how to tell if a supplement is working.

A simple routine for long-term supplement use

1. Use the label dose. The ODS warns that higher doses, taking many supplements at once, or using them in place of prescribed medicine all raise the risk of side effects.^[3]
2. Keep one written list of every supplement, dose and brand, and share it with your doctor, pharmacist and dentist.
3. Ask a pharmacist to check interactions whenever a new prescription is added.
4. Review once a year. At your checkup, ask whether you still need each product and whether routine blood work, such as liver enzymes, makes sense for you.
5. Stick with one tested brand instead of switching often, and keep the lot number.
6. Stop and call your doctor if a new symptom appears after starting something.

Who should talk to a doctor before long-term use

• Anyone taking a prescription drug, especially blood thinners, diabetes drugs, blood pressure drugs, statins, antidepressants, immunosuppressants or heart medicines such as digoxin.
• People with liver or kidney disease, a history of heavy alcohol use, or an autoimmune condition (NCCIH notes Asian ginseng may worsen autoimmune disorders).^[2]
• Anyone scheduled for surgery.^[3]
• People taking several supplements at the same time, since overlapping ingredients add up.

If you take Ultra Bann long term

Ultra Bann is a natural male vitality supplement by DL Bioproducts. The label directions are one capsule every 2 days, and every amount is disclosed with no proprietary blend: Thai Butea superba 345 mg, Panax ginseng 110 mg, Cynomorium songaricum 85 mg, black ginger (Kaempferia parviflora) 85 mg, tongkat ali 85 mg, epimedium (horny goat weed) 45 mg and reishi (Ganoderma lucidum) 45 mg, for 800 mg in total. You can review the full ingredient label before you buy.

The same long-term rules apply. Because it contains Panax ginseng, the ginseng cautions above (sleep changes, blood sugar, clotting and medication interactions) are worth discussing with your doctor if you plan to use it for many months, and our pages on Panax ginseng for men and tongkat ali side effects cover each herb in detail. Bring the label to your yearly checkup. First orders ship free in the US and include a 60-day money-back guarantee through the Ultra Bann shop.

Frequently Asked Questions

Can you take supplements forever?

Some people take the same supplement for years without problems, but “forever” is not something most herbs have been tested for. Treat long-term use as an ongoing decision: review each product with your doctor once a year, confirm you still benefit, and stop if new symptoms appear.

Should you cycle herbal supplements?

There is little research supporting fixed cycling schedules for most herbs. A periodic break can still be useful to check whether a product is helping and to spot side effects, as long as you follow the label and your clinician’s advice, especially if you take medication.

Which supplements cause liver damage?

In U.S. registry data, bodybuilding products were the most common supplement cause of liver injury.^[4] Green tea extract, turmeric, ashwagandha, garcinia cambogia, red yeast rice and black cohosh have also been linked to liver toxicity, and NIH ODS names kava and comfrey as botanicals that can harm the liver.^[3][6] Serious cases are rare relative to the number of users, but they can be severe.

What blood tests should I get if I take herbal supplements long term?

There is no universal schedule. Many doctors look at liver enzymes and kidney function as part of routine blood work, and they may check more often if you take several supplements or medications that affect the liver. Ask your doctor what fits your situation.

Is it safe to take ginseng every day?

NCCIH says short-term use of Asian ginseng by mouth, up to 6 months, appears safe for most people, while its long-term safety has been questioned. Insomnia is the most common side effect, and people with diabetes or who take any medicine should check with a clinician first.^[2]

References

1. National Center for Complementary and Integrative Health. Herb-Drug Interactions. NCCIH Clinical Digest, December 2024.
2. National Center for Complementary and Integrative Health. Asian Ginseng: Usefulness and Safety. Updated February 2025.
3. NIH Office of Dietary Supplements. Dietary Supplements: What You Need to Know. Updated January 4, 2023.
4. Mechcatie E. Liver injury from herbal and dietary supplements on the rise. Internal Medicine News (MDedge), November 5, 2013. Reporting DILIN data presented at The Liver Meeting 2013.
5. American Association for the Study of Liver Diseases. The Frequency of Herbal and Dietary Supplement Mislabeling. Newswise, October 20, 2017.
6. Straight Arrow News. As supplement use increases, so do cases of liver failure linked to them. May 28, 2025.
7. National Institute of Diabetes and Digestive and Kidney Diseases. LiverTox: Clinical and Research Information on Drug-Induced Liver Injury. NCBI Bookshelf, 2012 onward.

These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure or prevent any disease. This article is for information only and is not medical advice.