Certain herbs, such as pennyroyal, evening primrose, borage, eucalyptus and comfrey, are toxic to cats, but many herbs are beneficial for myriad conditions. Herbs come in many forms--such as tinctures, capsules, ointments and teas--and can be obtained from a holistic vet, some pet stores and natural health stores.
Ginger is soothing for an upset stomach. The Herbal Encyclopedia recommends giving cats a few drops of ginger root extract before leaving on a car trip and also administering another dose halfway through the ride for long trips.
Chamomile has anti-anxiety, anti-inflammatory and antispasmodic properties. It is useful as a sedative but is also good for abdominal cramps. Chamomile can be helpful for gastric ulcers, the irritation to the gastrointestinal tract from inflammatory bowel disease and skin abrasions, according to PetCareNaturally.com. The dosage of chamomile depends on how it is prepared and for what illness it is used.
Most cat owners are familiar with catnip and its purported ability to make cats "high." When inhaled, catnip acts as a stimulant, but if ingested, catnip is a sedative. According to Cat World, only about 50 percent of cats respond to catnip. The herb contains nepetalactone, a substance that causes hallucinations and also stimulates the production of pheromones normally released during sex. There is no set dosage for catnip, and cats can't overdose, according to Cat World.
Milk thistle is typically used to treat liver disease and to protect the liver. The website of Doctors' Foster and Smith attributes the protective and regenerative abilities of milk thistle to a compound within, called silymarin. Silymarin is an antioxidant that counters the cell damage from free radicals, which cause aging. Veterinarian Jean Hofve suggests that milk thistle be used to treat gallstones and IBD, to boost the immune system, and to reduce liver or bile duct inflammation in cats. Milk thistle might potentially inhibit tumor growth or treat diabetic neuropathy, based on results in humans. The usual dose is 80 to 200 mg daily of a milk thistle that contains at least 80 percent silymarin. Long-term usage of high doses may eventually harm the liver, Hofve says.
Slippery elm bark has several healing properties, making it a versatile herb for cats. The herb can be taken internally or used externally to promote healing and reduce the likelihood of infection. It is beneficial for inflammation of all the mucus membranes, such as the stomach, lungs, kidneys, joints, throat and bladder. Slippery elm contains pentosans, a component used to make Elmiron, a human medication prescribed to ease the pain of bladder spasms from cystitis. According to Hofve, the usual dose is one-quarter teaspoon of slippery elm powder per 10 lbs. of body weight.