Contrary to the belief that cats are tough, they are in fact quite delicate partly because their livers simply do not process food and supplements they way ours do. With cats, when it doubt, leave it out. Hope the following caveats and cautions regarding herbs, essential oils, alcohol, and preservatives help fellow cat lovers.

Herbs:

With cats, it is best to play it safe and with the exception of a few herbs, assume that most are either unsafe or at best used short-term, and all this only after a great deal of research.  In other words, all traditional contraindications apply and then some.

The few herbs that have a longer history of "safe" (I put this in quotes because no herb is totally safe, we have to weigh pluses and minuses) use are:

Safe Longer-term:

• Marshmallow Root and Slippery Elm Bark - for nausea, vomiting, diarrhea, and constipation. Great for IBD cats to help rebuild intestinal mucosa as well as for cats with CRF. Give at least 30-60 minutes prior to feeding to avoid nutrient absorption concerns.
• Stinging Nettles - for sneezing/hay fever symptoms
• Dandelion Leaf - for cats with Congestive Heart Failure (CHF)
• Aloe vera juice/gel (inner leaf)
• Catnip – appetite and mood stimulant
• Turmeric or curcumin – anti-inflammatory, emmanagogue/blood-moving for conditions such as cancer, and heart benefits.

Safe Short-term for medicinal purposes:

• Raspberry leaf – short-term use only for queens
• Arjuna – a cardiotonic
• Andrographis Paniculata – for sinus problems
• Astragalus – immune booster, also helpful for thyroid and kidney conditions
• Blackberry Leaf - diarrhea
• Boswellia - arthritis
• Cayenne – arthritis (some formulations can cause stomach pain)
• Cinnamon – lower blood glucose levels
• Cranberry – there isn’t much reason to use this herb for cats with FLUTD. A better option is D-Mannose for a few days. But since there are many formulas out there with Cranberry, just including this here…
• Dandelion leaf – diuretic containing high levels of potassium
• Echinacea – at the first signs of a cold
• Fennel – digestive upset
• Ginger - nausea
• Ginkgo Biloba – blood-thinner good for circulatory problems
• Ginseng – American and Siberian – immune system; colds; physical and mental stimulation
• Goldenseal - antibacterial
• Hawthorne berries - cardiotonic
• Parsley – diuretic that can cause potassium loss
• Milk Thistle – liver problems
• Peppermint Leaf – nausea and indigestion
• St. John's Wort - depression/mood
• Valerian – appetite stimulation

The following herbs should never be given to cats internally:

• Herbs containing salicin - White Willow Bark, Feverfew, and Meadowsweet
• Alfalfa - an ingredient in it - canavanine, can lead to abnormal blood cell counts and spleen enlargement as well as interfere with arginine uptake in the body. Arginine (abundant in meat) is critical for cats, and inadequate amounts of arginine can cause serious problems. See article titled "Why does the cat require a high protein diet?" by Rogers QR & Morris JG (1980) Journal of Nutrition 109, 718–723 for details on the deleterious effects of inadequate L-arginine in kitten diets. Last but not least, Alfalfa contains coumarin derivatives that can inhibit blood clotting. There is no reason to use this herb, none.
• Mistletoe - detrimental effect to the heart
• Pennyroyal - Check for this herb as one of the ingredients in those ubiquitous "flea collars"
• Strong bitters in “worming” formulas such as Rue, Feverfew, and Wormwood
• Comfrey - can cause liver damage (ok to use PA-free brands e.g. Herb Pharm's for external use)
• Chapparal - contraindicated for kidney and liver problems
• Lobelia - can cause nausea and vomiting

The following herbs can be okay but only with extra caution:

• Juniper Berries - should not be used long-term because it irritates the kidneys/urinary tract.
• Uva Ursi - has a strong astringent action, and should not be used long-term because it irritates the kidneys/urinary tract. Uva Ursi should only be used with alkaline urine. Even though we do not know for sure if cranberry acidifies the urine, do not use Uva Ursi together with
  cranberry.
• Horsetail - long-term use can elevate blood pressure
• Licorice - can lead to water retention and raise blood pressure. Best not to use on a long-term basis.
• Ginkgo - Do not use with allopathic heart medication/blood thinners
• Hawthorne Berry - Do not use with allopathic heart medication/blood thinners
• Red Clover – Contains coumarins which could affect bleeding problems in cats. Should not to be taken with allopathic blood thinning drugs
• Goldenseal, Barberry, and Oregon Grape Root - Strong astringent action; can kill off beneficial bacteria, so best for short-term use only.

Essential Oils:

Essential oils (EOs) from any plant should never be used on or near cats because EOs can burn their skin and cat livers are unable to process the terpenes in EOs. Please read this article on Aromatherapy by certified aromatherapist Kristen Leigh Bell for more details.

Alcohol:

Unlike humans, cats have not evolved consuming anything that contains naturally occurring alcohol. On my list, we have seen cats develop liver and pancreatitis problems when administered anything containing alcohol And that's stuff we can see, so who knows what sort of damage occurs over time..

Most homeopathic tincture preparations and flower essences contain at least 20% alcohol with LM tinctures containing 90-95% alcohol. This means it's not a good idea to use them neat other than topically. If using internally, a reasonable dilution rate might be no more than 2 drops per 15ml/1oz dropper bottle of water. If a weaker dilution works, e.g. 1 drop, try that first. Even better would be avoid the issue altogether and use pills/pellets instead.

Herbs can contain anywhere from 10% to 70% alcohol in certain tincture preparations, so using these without making sure the alcohol has been removed as much as possible is a bad idea. Freeze-dried capsules are usually the best bet with cats for this reason. For info on how to remove alcohol from a herbal tincture, stay tuned, an article will be added in the next week or so.

Other Cautions:

Beware of potassium sorbate and sodium benzoate as they are both unsafe for cats. Alas, both of these are common preservative in aloe vera juice and gel formulations. There is only one brand available without sodium benzoate - George's Aloe Vera Juice. Some Lily of the Desert varieties contains potassium sorbate, but there is one safe version which is their pure preservative-free aloe vera inner fillet (not whole leaf) juice..

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