Wild cherry bark (Prunus serotina, P. virginiana) also known as choke cherry, is one of several herbal remedies that contain amygdalin, also called prunasin, a toxic glycoside found in the seeds of many species of Rosaceae including bitter almonds, peaches, apricots and loquat, an herb used in Traditional Chinese Medicine (TCM) to assuage coughing. It is also found in blackberry leaves.
The unique property of prunasin is its ability to inhibit the cough reflex, especially for dry coughs, which in recent years has been one of the more serious long-term complications in the aftermath of influenza. A tea of wild cherry bark and coltsfoot is one of the most effective treatments for asthma, bronchitis and whooping cough, which has swept throughout sectors of the US in recent months.
Cyanogenic Glycoside Risks and Toxicity
An enzymatic reaction changes the non-toxic cyanogenic glycosides in wild cherry and other herbs containing this component to its more toxic form, hydrogen cyanide (HCN).
Clinical symptoms of cyanide poisoning include cyanosis caused by lack of oxygen in bodily tissues, severe headaches, stupor, convulsions, collapse and respiratory paralysis leading to death. Cyanide can be lethal to humans at the dose of 1 mg/kg of body weight.
While herbalists champion the use of wild cherry bark in tea and alcoholic tincture extracts as a sovereign remedy for coughs, confusion arises when authors describing edible plants are likely to emphasize wild cherry’s potential toxic properties. Thus, for the herbalist and consumer, this herb in particular comes with serious mixed messages to wade through. This is a case where the old adage "the poison is in the dose" holds true. Wild cherry inner bark can be used safely, as its history as medicine, discussed below, attests.
Historical and Modern Use of Wild Cherry
The medicinal uses of wild cherry bark was first learned by the settlers from Native Americans throughout the US continent. In fact, they treated Merriwether Lewis on his famous expedition for a serious gastrointestinal illness with a twig tea of wild cherry bark. Native people are on record using it as a general GI tonic, a treatment for diarrhea and sore throat, as a purgative, for coughs and colds, and applied topically to stop bleeding.
Many caution against its use for pregnant mothers and children under two years of age, but Native Americans used wild cherry to ease labor pains and gave it to nursing mothers who "drank the tea to pass the medicinal effects on to their infants." 
Wild cherry bark was listed as official in the US Pharmacopeia from 1820 to 1970 – arguably a more enlightened period before Big Pharma systematically set about replacing herbal drugs with synthetics.
I often recommend heroic doses of herbs especially in acute conditions to effect rapid recovery. This herb would be an exception. The tea is made by steeping 2 teaspoons of wild cherry bark in 1 cup of boiling water for 10 minutes; drinking approximately 3 cups daily would be safe. Of the tincture, anywhere from 30 to 60 drops three times daily would also be fine.
Wild cherry bark has many other uses besides being a cough inhibitor. It is used as a treatment for sore throat, colds, and as an astringent to stop bleeding, diarrhea and hemorrhoids. It can also be used as a digestive stimulant and for the treatment of jaundice.
The same properties that calm dry irritable coughs is also effective for nervous palpitations so that wild cherry bark serves as a mild sedative to the circulatory and nervous systems as well as other mucosal surfaces including those of the gastro intestinal and urinary tracts. Externally, fomentations of the tea of the bark can be applied to allay pain and promote the healing of inflammation associated with injuries and burns. David Hoffmann recommends an ointment as a treatment for hemorrhoids and cuts. Last but not least, the anti-inflammatory properties of wild cherry bark has been found particularly effective as an eyewash for inflamed eyes.
I have used wild cherry bark usually in formula mostly in the form of a tea or syrup for coughs and upper respiratory disease for over 30 years for people of all ages. I have it in formula in my Old Indian Cough Syrup (Planetary Herbs).
I have had innumerable patients suffering from asthma and chronic emphysema make up a tea of a handful of equal parts of the following dried herbs simmered for 20 minutes in a quart of water:
Wild cherry bark
A quarter part lobelia herb
Several slices of raw ginger
One man with emphysema took this daily for over a year and attributed the fact that he could go on long walks without suffering from shortness of breath as a result of its use. He showed no sign of toxicity from wild cherry.
So, despite the cautions and warnings that one might encounter about Wild cherry bark I and every herbalist I know consider this herb both effective and safe.
I recently queried a number of herbalists and students on the American Herbalists Guild forum about their favorite uses for wild cherry bark and received the following:
From Rosanna King – "I gave a teaspoon of wild cherry bark tincture to my roommate one night when her coughing was keeping me awake. She had a dry, ticklish, non-productive , annoying cough. Effects were immediate and lasted all night."
From Suki Roth – "I infuse the dry bark in honey (warmed to 90 degrees). Let that sit warm for 24 hours...strain and then add elecampane."
From Christa Sinadinos – "My favorite preparation for cherry bark syrup is a double water percolation, one I learned from an old pharmacopoeia. The first percolation drips water through the cone, into a second cone filled with, you guessed it, good old fashioned sugar (use organic if it makes you feel better). By the time it finishes dripping, you're left with a delicious almond tasting syrup that masks the bitterness of the cherry bark. I've used it for kids and adults as a respiratory antispasmodic/anti-tussive, expectorant, and to reduce sore throat. It has worked well as secondary support for pertussis, dry hacking coughs, a tickle in the throat, tension in the chest, and mild wheezing that accompanies a respiratory infection.
Another effective preparation is the cold infusion of cherry bark, but it is bitter as all get out...and I can't get patients to comply unless they sweeten it. I've made a number of tincture preparations and glycerites, but they are not anywhere near as effective as the first syrup or the cold infusion. I have not seen toxicity from using it so far."
And finally from Susan Marynowski – "I also find wild cherry to be very calming to the heart."
 Clover farms - http://www.cloverleaffarmherbs.com/black-cherry/#sthash.Tz6S3aQJ.dpbs
Field Guide to Medicinal Wild Plants – Bradford Angier (1978)
Buddha Teas – Wild Cherry bark Tea - http://www.wildcherrybark.net
Horse Nutrition - http://www.understanding-horse-nutrition.com/cherry.html
 Herbal Medicine – Menzies and Trull (2003)