Routes of administration
See also: Drying of herbs and spices
The exact composition of a herbal product is influenced by the method of extraction. A tisane will be rich in polar components because water is a polar solvent. Oil on the other hand is a non-polar solvent and it will absorb non-polar compounds. Alcohol lies somewhere in between. There are many forms in which herbs can be administered, these include:
- Tinctures - Alcoholic extracts of herbs such as echinacea extract. Usually obtained by combining 100% pure ethanol (or a mixture of 100% ethanol with water) with the herb. A completed tincture has a ethanol percentage of at least 40-60% (sometimes up to 90%). 
- Herbal wine and elixirs - These are alcoholic extract of herbs; usually with an ethanol percentage of 12-38%  Herbal wine is a maceration of herbs in wine, while an elixir is a maceration of herbs in spirits (e.g., vodka, grappa, etc.)
- Tisanes - Hot water extracts of herb, such as chamomile.
- Decoctions - Long-term boiled extract of usually roots or bark.
- Macerates - Cold infusion of plants with high mucilage-content as sage, thyme, etc. Plants are chopped and added to cold water. They are then left to stand for 7 to 12 hours (depending on herb used). For most macerates 10 hours is used.
- Vinegars - Prepared at the same way as tinctures, except using a solution of acetic acid as the solvent.
- Essential oils - Application of essential oil extracts, usually diluted in a carrier oil (many essential oils can burn the skin or are simply too high dose used straight – diluting in olive oil or another food grade oil can allow these to be used safely as a topical).
- Salves, oils, balms, creams and lotions - Most topical applications are oil extractions of herbs. Taking a food grade oil and soaking herbs in it for anywhere from weeks to months allows certain phytochemicals to be extracted into the oil. This oil can then be made into salves, creams, lotions, or simply used as an oil for topical application. Any massage oils, antibacterial salves and wound healing compounds are made this way.
- Poultices and compresses - One can also make a poultice or compress using whole herb (or the appropriate part of the plant) usually crushed or dried and re-hydrated with a small amount of water and then applied directly in a bandage, cloth or just as is.
- Whole herb consumption - This can occur in either dried form (herbal powder), or fresh juice, (fresh leaves and other plant parts). Just as Hippocrates said "Let food be thy medicine", it has become clear that eating vegetables also easily fits within this category of getting health through consumables (besides medicinal herbs). All of the vitamins, minerals and antioxidants are phytochemicals that we are accessing through our diet. There are clearly some whole herbs consumed that are more powerful than others. Shiitake mushrooms boost the immune system and are also tasty so they are enjoyed in soups or other food preparations for the cold and flu season. Alfalfa is also considered a health food.. Garlic lowers cholesterol, improves blood flow, fights bacteria, viruses and yeast.
- Syrups - Extracts of herbs made with syrup or honey. Sixty five parts of sugar are mixed with 35 parts of water and herb. The whole is then boiled and macerated for three weeks.
- Extracts - Include liquid extracts, dry extracts and nebulisates. Liquid extracts are liquids with a lower ethanol percentage than tinctures. They can (and are usually) made by vacuum distilling tinctures. Dry extracts are extracts of plant material which are evaporated into a dry mass. They can then be further refined to a capsule or tablet.  A nebulisate is a dry extract created by freeze-drying.
- Inhalation as in aromatherapy can be used as a mood changing treatment to fight a sinus infection or cough , or to cleanse the skin on a deeper level (steam rather than direct inhalation here)
 Examples of plants used as medicine
Main article: List of plants used as medicine
Few herbal remedies have conclusively demonstrated any positive effect on humans, mainly because of inadequate testing. Many of the studies cited refer to animal model investigations or in-vitro assays and therefore cannot provide more than weak supportive evidence.
- Aloe vera has traditionally been used for the healing of burns and wounds. A systematic review (from 1999) states that the efficacy of aloe vera in promoting wound healing is unclear, while a later review (from 2007) concludes that the cumulative evidence supports the use of aloe vera for the healing of first to second degree burns.
- Agaricus blazei mushrooms may prevent some types of cancer.
- Artichoke (Cynara cardunculus) may reduce production cholesterol levels according to in vitro studies  and a small clinical study.
- Blackberry (Rubus fruticosus) leaf has drawn the attention of the cosmetology community because it interferes with the metalloproteinases that contribute to skin wrinkling.
- Black raspberry (Rubus occidentalis) may have a role in preventing oral cancer.
- Butterbur (Petasites hybridus)
- Calendula (Calendula officinalis) has been used traditionally for abdominal cramps and constipation. In animal research an aqueous-ethanol extract of Calendula officinalis flowers was shown to have both spasmolytic and spasmogenic effects, thus providing a scientific rationale for this traditional use. There is "limited evidence" that calendula cream or ointment is effective in treating radiation dermatitis.
- Cranberry (Vaccinium oxycoccos) may be effective in treating urinary tract infections in women with recurrent symptoms.
- Echinacea (Echinacea angustifolia, Echinacea pallida, Echinacea purpurea) extracts may limit the length and severity of rhinovirus colds; however, the appropriate dosage levels, which might be higher than is available over-the-counter, require further research.
- Elderberry (Sambucus nigra) may speed the recovery from type A and B influenza. However it is possibly risky in the case of avian influenza because the immunostimulatory effects may aggravate the cytokine cascade.
- Feverfew (Chrysanthemum parthenium) is sometimes used to treat migraine headaches. Although many reviews of Feverfew studies show no or unclear efficacy, a more recent RTC showed favorable results Feverfew is not recommended for pregnant women as it may be dangerous to the fetus.
- Gawo (Faidherbia albida), a traditional herbal medicine in West Africa, has shown promise in animal tests 
- Garlic (Allium sativum) may lower total cholesterol levels
- German Chamomile (Matricaria chamomilla) has demonstrated antispasmodic, anxiolytic, antiinflammatory and some antimutagenic and cholesterol-lowering effects in animal research. In vitro chamomile has demonstrated moderate antimicrobial and antioxidant properties and significant antiplatelet activity, as well as preliminary results against cancer. Essential oil of chamomile was shown to be a promising antiviral agent against herpes simplex virus type 2 (HSV-2) in vitro. 
- Ginger (Zingiber officinale), administered in 250 mg capsules for four days, effectively decreased nausea and vomiting of pregnancy in a human clinical trial.
- Green tea (Camelia sinensis) components may inhibit growth of breast cancer cells and may heal scars faster.
- Purified extracts of the seeds of Hibiscus sabdariffa Roselle may have some antihypertensive, antifungal and antibacterial effect. Toxicity tested low except for an isolated case of damage to the testes of a rat after prolonged and excessive consumption.
- Honey may reduce cholesterol. May be useful in wound healing.
- Lemon grass (Cymbopogon citratus), administered daily as an aqueous extract of the fresh leaf, has lowered total cholesterol and fasting plasma glucose levels in rats, as well as increasing HDL cholesterol levels. Lemon grass administration had no effect on triglyceride levels. 
- Milk thistle (Silybum marianum) extracts have been recognized for many centuries as "liver tonics.". Research suggests that milk thistle extracts both prevent and repair damage to the liver from toxic chemicals and medications.
- Nigella sativa (Black cumin) coughing has demonstrated analgesic properties in mice. The mechanism for this effect, however, is unclear. In vitro studies support antibacterial, antifungal, anticancer, anti-inflammatory and immune modulating effects. However few randomized double blind studies have been published.
- Ocimum gratissimum and tea tree oil can be used to treat acne.
- Oregano (Origanum vulgare) may be effective against multi-drug resistant bacteria.
- Pawpaw can be used as insecticide (killing lice, worms).,
- Peppermint oil may have benefits for individuals with irritable bowel syndrome.
- Phytolacca or Pokeweed is used as a homeopathic remedy to treat many ailments. It can be applied topically or taken internally. Topical treatments have been used for acne and other ailments. It is used to treatment tonsilitis, swollen glands and weight loss.
- Pomegranate contains the highest percentage of ellagitannins of any commonly consumed juice. Punicalagin, an ellagitannin unique to pomegranate, is the highest molecular weight polyphenol known. Ellagitannins are metabolized into urolithins by gut flora, and have been shown to inhibit cancer cell growth in mice.
- Rauvolfia Serpentina, high risk of toxicity if improperly used, used extensively in India for sleeplessness, anxiety, and high blood pressure.
- Rooibos (Aspalathus linearis) contains a number of phenolic compounds, including flavanols, flavones, flavanones, flavonols, and dihydrochalcones. Rooibos has traditionally been used for skin ailments, allergies, asthma and colic in infants. In an animal study with diabetic mice, aspalathin, a rooibos constituent improved glucose homeostasis by stimulating insulin secretion in pancreatic beta cells and glucose uptake in muscle tissue.
- Rose hips – Small scale studies indicate that hips from Rosa canina may provide benefits in the treatment of osteoarthritis. Rose hips show anti COX activity.
- Salvia lavandulaefolia may improve memory
- Saw Palmetto can be used for BPH. Supported in some studies, failed to confirm in others.
- Shiitake mushrooms (Lentinus edodes) are edible mushrooms that have been reported to have health benefits, including cancer-preventing properties. In laboratory research a shiitake extract has inhibited the growth of tumor cells through induction of apoptosis. Both a water extract and fresh juice of shiitake have demonstrated antimicrobial activity against pathogenic bacteria and fungi in vitro.
- Soy and other plants that contain phytoestrogens (plant molecules with estrogen activity) (black cohosh probably has serotonin activity) have some benefits for treatment of symptoms resulting from menopause.
- St. John's wort, has yielded positive results, proving more effective than a placebo for the treatment of mild to moderate depression in some clinical trials A subsequent, large, controlled trial, however, found St. John's wort to be no better than a placebo in treating depression However, more recent trials have shown positive results or positive trends that failed significance. A 2004 meta-analysis concluded that the positive results can be explained by publication bias but later analyses have been more favorable. The Cochrane Database cautions that the data on St. John's wort for depression are conflicting and ambiguous.
- Stinging nettle In some clinical studies effective for enign prostatic hyperplasia and the pain associated with osteoarthritis. In-vitro tests show antiinflammatory action. In a rodent model, stinging nettle reduced LDL cholesterol and total cholesterol.  In another rodent study it reduced platelet aggregation.
- Valerian root can be used to treat insomnia. Clinical studies show mixed results and researchers note that many trials are of poor quality.