Supplements and herbs

What popular herbs and supplements are promoted for, what the evidence says, and the safety cautions. Natural does not always mean safe, and many products interact with medicines. AskBioMap does not sell, recommend or promote any supplement or brand.

Safety notices from the TGA

Vitamin B6 can cause nerve damage called peripheral neuropathy. Stop taking it and talk to your doctor if you notice tingling, burning or numbness. Read the TGA notice on vitamin B6.

Rare cases of liver injury have been linked with ashwagandha. Stop and seek medical advice if you notice yellow skin or eyes, dark urine or unusual tiredness. Read the TGA notice on ashwagandha.

Before you take a supplement

Tell your doctor and pharmacist about every supplement and herbal product you take.
Check for interactions with your medicines, especially blood thinners, antidepressants and the contraceptive pill.
Take extra care in pregnancy and while breastfeeding, and ask before giving any supplement to someone else.

Herbs and supplements A to Z

Aloe vera Emerging

Aloe vera

Promoted for: Burns and skin conditions (gel), and weight, diabetes and bowel conditions (by mouth).
The evidence: Gel on the skin may speed burn healing and reduce burn pain. Evidence for taking aloe by mouth is small.
Cautions: Aloe latex taken by mouth causes cramps and diarrhoea. Oral leaf extracts have been linked with hepatitis, and oral aloe may be unsafe in pregnancy and while breastfeeding.
Source: NIH NCCIH, Aloe vera

Ashwagandha Emerging

Withania somnifera

Promoted for: Stress and anxiety, sleep, male fertility and athletic performance.
The evidence: Some preparations may help insomnia and stress. The effect on anxiety is unclear.
Cautions: The TGA reports very rare cases of liver injury. Stop and seek medical advice if you notice signs of liver problems, and avoid it if you have or have had liver problems. It should be avoided in pregnancy and while breastfeeding, and is not recommended with thyroid or autoimmune conditions. It may interact with diabetes, blood pressure, thyroid and sedative medicines.
On the map: Ashwagandha
Sources: NIH NCCIH, Ashwagandha; Therapeutic Goods Administration, Withania somnifera (ashwagandha) and liver injury

Asian ginseng Emerging

Panax ginseng

Promoted for: Stress, thinking, fatigue, athletic performance and diabetes.
The evidence: Research is small and short. Results for blood sugar are conflicting, and most studies show no benefit for athletic performance.
Cautions: Trouble sleeping is the most common side effect. It may lower blood sugar, may interfere with blood clotting and may be unsafe in pregnancy. Check with your pharmacist if you take any medicine.
Source: NIH NCCIH, Asian ginseng

Black cohosh Emerging

Actaea racemosa

Promoted for: Menopause symptoms.
The evidence: A 2023 review found products with black cohosh extract may help overall menopause symptoms, including hot flushes, but not anxiety or low mood.
Cautions: There are rare reports of liver damage, some serious. Seek medical advice if you notice dark urine or tiredness. Some products have contained the wrong herb. May not be safe in pregnancy or while breastfeeding.
Source: NIH NCCIH, Black cohosh

Chamomile Emerging

Matricaria chamomilla

Promoted for: Colds, indigestion, anxiety and sleep.
The evidence: Studies have not produced enough reliable evidence to rate its usefulness, and there is very little information on sleep.
Cautions: Likely safe in tea amounts. Allergic reactions are possible, more so in people allergic to ragweed, chrysanthemums, marigolds or daisies. Interactions with warfarin have been reported.
Source: NIH NCCIH, Chamomile

Chasteberry Emerging

Vitex agnus-castus

Promoted for: Premenstrual symptoms and cyclic breast pain.
The evidence: Some studies suggest it may reduce premenstrual symptoms such as breast tenderness, but higher-quality evidence is needed.
Cautions: Side effects are usually mild, such as nausea, stomach pain or headache. It may not be safe with hormone-sensitive conditions, and may be unsafe in pregnancy or while breastfeeding.
Source: NIH NCCIH, Chasteberry

Cinnamon Contested

Cinnamomum species

Promoted for: Diabetes and weight loss.
The evidence: Research does not clearly support cinnamon for any health condition, including blood sugar control.
Cautions: Cassia cinnamon contains coumarin, and some products contain high levels, a concern for people with liver disease. Never eat cinnamon powder as a dare, because serious harm is possible.
Source: NIH NCCIH, Cinnamon

Echinacea Emerging

Echinacea purpurea and related species

Promoted for: Colds and other respiratory infections.
The evidence: It may slightly reduce the chance of catching a cold. It is unclear whether it shortens a cold.
Cautions: Allergic reactions can occur and may be severe. Stomach upset and nausea are the most common side effects. Talk to a doctor before giving it to children.
Source: NIH NCCIH, Echinacea

Elderberry Emerging

Sambucus nigra

Promoted for: Colds and flu.
The evidence: Some early research suggests it may relieve symptoms of flu, colds or other upper respiratory infections. There is no good evidence for COVID-19.
Cautions: Raw or unripe berries, leaves and stems contain substances that release cyanide and can cause vomiting and severe diarrhoea.
Source: NIH NCCIH, European elder (elderberry)

Fenugreek Emerging

Trigonella foenum-graecum

Promoted for: Diabetes, period pain and breast milk supply.
The evidence: The evidence for diabetes is not enough to draw conclusions, and results for breast milk supply are mixed.
Cautions: Large doses may cause a harmful drop in blood sugar. Not safe in pregnancy in amounts larger than those in food. Allergic reactions can be serious.
Source: NIH NCCIH, Fenugreek

Flaxseed and flaxseed oil Emerging

Linum usitatissimum

Promoted for: Heart, brain and immune health.
The evidence: Research is limited. One trial suggests flaxseed mucilage powder mixed with water might support weight loss.
Cautions: Do not eat raw or unripe flaxseeds. Higher doses may cause bloating and diarrhoea. Check with your pharmacist if you take blood thinners. Flaxseed may be unsafe in pregnancy.
Source: NIH NCCIH, Flaxseed and flaxseed oil

Garlic Emerging

Allium sativum

Promoted for: Cholesterol, blood pressure, diabetes and immunity.
The evidence: Garlic supplements may lower total and LDL cholesterol, and blood pressure, to a small extent in people with high levels.
Cautions: May increase the risk of bleeding. Tell your doctor before surgery, and check first if you take blood thinners or aspirin. Supplement doses may not be safe in pregnancy.
Source: NIH NCCIH, Garlic

Ginger Emerging

Zingiber officinale

Promoted for: Nausea and vomiting, osteoarthritis and period pain.
The evidence: Ginger may help nausea and vomiting in pregnancy and may reduce period pain. Most studies have not shown it helps motion sickness.
Cautions: Side effects can include stomach discomfort, heartburn and diarrhoea. Check with your doctor or midwife before taking it in pregnancy, and with your pharmacist if you take any medicine.
Source: NIH NCCIH, Ginger

Ginkgo Contested

Ginkgo biloba

Promoted for: Thinking, anxiety, heart disease and many other conditions.
The evidence: There is no conclusive evidence that ginkgo helps any health condition. Large studies found it did not reduce the risk of dementia.
Cautions: May increase bleeding risk in people taking blood thinners such as warfarin. Ginkgo seeds are toxic. May be unsafe in pregnancy.
Source: NIH NCCIH, Ginkgo

Goldenseal and berberine Emerging

Hydrastis canadensis

Promoted for: Colds and other upper respiratory infections.
The evidence: Berberine, a substance in goldenseal, has been studied for its effects on blood sugar, blood cholesterol and body weight.
Cautions: The berberine in goldenseal can be harmful to newborns, so it should not be used in pregnancy or while breastfeeding. Talk with your doctor before using it.
On the map: Berberine
Source: NIH NCCIH, Goldenseal

Green tea and green tea extract Emerging

Camellia sinensis

Promoted for: Weight loss and other uses.
The evidence: The catechins and caffeine in green tea may have a modest effect on body weight. No safety concerns have been reported for green tea as a drink for adults.
Cautions: Liver injury has been reported in some people using green tea products, mainly concentrated extracts. Green tea contains caffeine.
Source: NIH NCCIH, Green tea

Kava Emerging

Piper methysticum

Promoted for: Anxiety.
The evidence: Kava may ease anxiety, but it does not appear to help the symptoms of generalised anxiety disorder.
Cautions: Kava has been linked with rare liver injury, some of it serious or fatal. Never combine it with alcohol or sedatives such as benzodiazepines. It may carry special risks in pregnancy.
Source: NIH NCCIH, Kava

Licorice root Emerging

Glycyrrhiza glabra

Promoted for: Digestive, respiratory and energy support.
The evidence: There is not enough high-quality evidence to support licorice for any health condition.
Cautions: Glycyrrhizin in licorice can cause serious effects such as an irregular heartbeat, especially with large or long-term use, and even small amounts can be risky with high blood pressure or heart or kidney disease. Large amounts in pregnancy are unsafe.
Source: NIH NCCIH, Licorice root

Milk thistle Contested

Silybum marianum

Promoted for: Liver problems and diabetes.
The evidence: There is not enough high-quality evidence to draw firm conclusions. Two NIH-funded studies, in hepatitis C and in a form of fatty liver disease, found no benefit.
Cautions: Usually well tolerated, with bloating, nausea or wind in some people. Allergic reactions are possible. Product quality varies.
Source: NIH NCCIH, Milk thistle

Peppermint oil Supported

Mentha x piperita

Promoted for: IBS, indigestion, headaches and nausea.
The evidence: Enteric-coated peppermint oil capsules may improve IBS symptoms in adults, doing better than placebo for overall symptoms and tummy pain in a 2022 review.
Cautions: Can cause heartburn, nausea and tummy pain. Never apply the oil to the face of a baby or young child.
Source: NIH NCCIH, Peppermint oil

Rhodiola Emerging

Rhodiola rosea

Promoted for: Athletic performance, mood, thinking, energy and stress.
The evidence: There is not enough reliable evidence to know whether rhodiola helps any health condition.
Cautions: Possibly safe for up to 12 weeks. Side effects include dizziness, headache and trouble sleeping. An interaction with the blood pressure medicine losartan has been reported.
Source: NIH NCCIH, Rhodiola

Saw palmetto Contested

Serenoa repens

Promoted for: Urinary symptoms from an enlarged prostate.
The evidence: NCCIH says it is probably not helpful for this. A review of 27 studies found little or no benefit, and two NIH-funded trials, one at up to three times the usual dose, found no improvement.
Cautions: Usually well tolerated. Urinary symptoms should be checked by a doctor. May be unsafe in pregnancy or while breastfeeding.
Source: NIH NCCIH, Saw palmetto

St John's wort Supported

Hypericum perforatum

Promoted for: Depression, and menopause symptoms.
The evidence: Studies suggest it may help mild to moderate depression, doing better than placebo. It is uncertain whether it helps severe depression.
Cautions: It weakens many medicines, including the contraceptive pill, some antidepressants, some heart, HIV, transplant and cancer medicines, and warfarin. With some antidepressants it can cause serious serotonin-related side effects. It may be unsafe in pregnancy. Never use it without checking with a doctor or pharmacist.
Source: NIH NCCIH, St. John's wort

Turmeric and curcumin Emerging

Curcuma longa

Promoted for: Promoted as a supplement for a variety of conditions, including osteoarthritis.
The evidence: For osteoarthritis the initial evidence is positive, but higher-quality evidence is needed. NCCIH says we do not know enough to conclude that turmeric or curcumin is beneficial for any health purpose.
Cautions: Highly absorbable curcumin products may harm the liver. Stop immediately if you notice dark urine or jaundice. Turmeric supplements may be unsafe in pregnancy.
On the map: Turmeric and curcumin
Source: NIH NCCIH, Turmeric

Valerian Contested

Valeriana officinalis

Promoted for: Insomnia, anxiety, stress and depression.
The evidence: Evidence on sleep is inconsistent, and the American Academy of Sleep Medicine recommends against valerian for long-term insomnia in adults. There is not enough evidence on anxiety.
Cautions: Side effects include headache, stomach upset and vivid dreams. Liver injury has been reported in very rare cases. Do not take it with alcohol or sedatives.
Source: NIH NCCIH, Valerian

Supplements on the map

The summaries are AskBioMap's own plain-English overview of the evidence, with a link to the full fact sheet for each product. General education only, not a recommendation to take any product.