Always check with your kidney team before taking any vitamins, supplements or herbal medicines
This page contains information about different types of vitamins, supplements and herbal remedies. It is intended as a general overview. For specific advice, speak to your kidney team or pharmacist.
"Vitamins and herbal medicines are not harmless," says Cathy Pogson, a specialist renal pharmacist at Portsmouth Hospitals University NHS Trust.
"For people with kidney disease, in certain situations, they may cause harm. This affects everyone differently. It depends on the product, what medicines you are taking and your kidney disease.
"To avoid harm, please check with your kidney team before taking anything, even if it seems innocuous. They may, for example with vitamins, be able to offer you a safe alternative on prescription."
Why can vitamins and herbal medicines be dangerous when you are living with chronic kidney disease (CKD) or after a transplant?
Substances can build up as kidneys are unable to remove them
"Living with kidney disease means that you can't remove some products from the blood. This means the products may build up in your body and this may cause harm," says Cathy.
Risk to your regular medicines
Herbal supplements may interact with prescription medicines and affect how the medicine works. "Vitamins and supplements may alter the other medicines you take," explains Ravinder Sagoo, clinical lead renal dietitian at Nottingham University Hospital Trust.
"Many medicines may need careful monitoring," adds Cathy. "For example, tacrolimus, a drug that suppresses the immune system, or warfarin, a blood thinner. Please check with the kidney team before taking any vitamins or herbal medicines."
Vitamins and supplements are not controlled in the same way as medicines are
The Medicines and Healthcare products Regulatory Agency (MHRA) does not regulate herbal supplements for dose, content, or purity of ingredients. "Supplements and herbal remedies abide by food standards. Food standards are lower than medicine standards," explains Ravinder. "Products bought over the internet may bypass these standards. They may contain other ingredients including lead, aristolochic acid and mercury, which can all be harmful. These are not in products bought in the UK."
What is herbal medicine?
Herbal medicines come from fresh or dried medicinal plants, explains Cathy.
"Herbal medicines may have a full medicine licence (for example, senna) which you can get on a prescription. Or you can buy them over the counter at a pharmacy, or from a health food shop," says Cathy.
"These products do not have to prove they have any benefit. Medicine products have a patient information leaflet inside the box. Food supplements will not."
Banned ingredients include those known to cause harm to the kidneys, liver, and nerves (including the brain). "Choosing licensed or registered products avoids much of this risk. Banned ingredients may be in products bought over the internet," says Cathy.
Which herbal supplements might cause drug interactions?
Many herbal supplements can interact with prescription drugs. Examples include blue cohosh, echinacea, ginseng, melatonin, St. John’s Wort, CBD (cannabidiol), and starfruit.
"Herbal supplements can affect all the medicines you are taking. If you have a transplant this can be very risky. An interaction can increase the chance of your body rejecting your kidney," says Cathy.
Cannabidiol (CBD)
"CBD is available without sales restrictions. This is a product which may alter your medicine. It interacts with tacrolimus," says Cathy.
Turmeric
"Turmeric is thought to be anti-inflammatory. Joint pain can affect people who live with kidney disease. It may help with symptoms people experience,’ says Ravinder. "It may improve gut symptoms, reduce oxidative stress, and inflammation.
"Turmeric is safe in a tea or in curry, but taking lots of turmeric, over a long time, increases the chance of kidney stones. This risk depends on the stage of kidney disease. Do discuss with your kidney team.
"Some turmeric supplements also have black pepper or ginger added. This may increase the amount of turmeric you get and increase the chances of kidney stones."
Can traditional Chinese medicines be harmful if you have kidney disease or have had a transplant?
Chinese herbs may cause harm. Please ask your kidney team before taking them.
‘For example, Schisandra, a traditional Chinese medicine, may interact and increase levels of medicines which suppress the immune system," says Ravinder.
"Discuss any Chinese medicines or herbal medicines with your kidney team. They may affect your regular medicines and/or cause you harm."
Can any other natural remedies cause problems?
Natural remedies that are frequently asked about include:
- Nytol. There are two versions of Nytol sleep aids. The non-herbal remedy contains diphenhydramine hydrochloride. This is an antihistamine sold as a sleep remedy. "People who live with kidney disease should be careful. They may be sensitive to this product. It may build up in the body. This increases the risk of falls," says Ravinder. "The herbal Nytol contains valerian which may increase the effect of other medicines."
- Cod liver oil. "Cod liver oil may have anti-inflammatory benefit for joints, but it contains high amounts of vitamin A, which may cause harm to people receiving dialysis or with low kidney function, so they should not take it," says Ravinder. "If you have joint problems, talk to your kidney team about safer alternatives."
Which vitamins are safe to take?
- "Don't take supplements containing vitamin A and E. They can build up in the body. The kidney team can give you safer alternatives," says Cathy.
- "It is important to get Vitamin D levels at the right level and your kidney team will check your vitamin D levels regularly. You may require prescription medicines for this such as alfacalcidol, but don't buy supplements yourself, the kidney team will offer you the right sort," explains Cathy.
- "Vitamin B and C are usually safe," says Ravinder. "But your kidneys may be unable to remove large amounts of vitamin C. Doses over 500mg can cause harm as there is an increased chance of developing kidney stones. The recommended daily maximum is 60mg vitamin C per day. This applies if you are pre dialysis or have had a transplant."
- Biotin or vitamin B7 supplements are sometimes used to treat hair loss. "They are generally very safe. Small doses of the B complex form are fine," says Ravinder. "We don't know the safe upper limit doses of vitamin B7. You should try to get this from food sources first. It is found in beef, liver, eggs, nuts, and sweet potato."
Are herbal teas safe if you have kidney disease or after a transplant?
"Packaged herbal and fruit teas are usually safe for people with kidney disease. The ingredients are diluted. Camomile, ginger, peppermint, mint, turmeric, and green tea are safe," says Ravinder.
"Don't make your own herbal teas from raw ingredients though, especially if you have had a transplant. These teas can be poisonous. Dandelion tea may be suitable for some people but please discuss with your kidney team before considering," adds Ravinder.
"Avoid liquorice teas; they may increase blood pressure and potassium levels."