Yes. Morning glory seeds are classed as harmful if eaten, for people and for pets. The Royal Horticultural Society labels Ipomoea tricolor 'Heavenly Blue' "Harmful if eaten" and advises gloves when handling the plant (RHS). The risk comes from the ergoline alkaloids in the seeds (see what is in the seeds) and, for garden-centre seed, possibly from chemicals used to coat it. Growing the plant and handling it with ordinary care is not the problem; swallowing the seeds is.
What swallowing the seeds can cause
North Carolina State Extension lists the symptoms after ingestion as "hallucinations, dilated pupils, nausea, vomiting, diarrhea, and drowsiness" (NC State Extension). The published case literature is small and mostly old, but it points the same way.
Nausea and vomiting. These appear on every list of symptoms we found, from the extension sheet above to the ASPCA's entry for animals below.
Effects on blood vessels. Lysergic acid amide constricted blood vessels in laboratory tests on animal tissue, in a similar way to the ergot alkaloids ergometrine and ergotamine (Oliver et al., 1993). Ipomoea tricolor seeds also contain ergometrine itself (Hofmann, 1963). In a German study with seeds of a related plant, Hawaiian baby woodrose, that contain the same main alkaloid, the researchers stopped after three of four healthy volunteers had serious adverse reactions, two of them a disturbance of heart rate and blood pressure and one a psychosis-like state. Reactions differed widely between people who took the same amount per kilogram of body weight (Kremer et al., 2012).
Psychiatric reactions. The first medical reports on morning glory seeds date from the 1960s in the United States, when morning glory seeds were briefly in the news. They include a suicide after ingestion (Cohen, 1964), a report on "morning glory seed reaction" in the Journal of the American Medical Association (Ingram, 1964) and a paper on psychosis after ingestion in the Archives of General Psychiatry (Fink, Goldman and Lyons, 1966). A 2013 review of Polish user reports found suicidal thoughts described in two cases after seeds of morning glory or Hawaiian baby woodrose (Juszczak and Swiergiel, 2013).
Unpredictable content. The amount of alkaloid differs between packets and between single seeds from the same packet, and some packets sold under the name contain none (Nowak et al., 2016). There is no way to tell from the outside of a seed what it contains.
Who is most at risk
- Children. Seeds look like something to put in the mouth and garden seed is often stored in kitchens and sheds. Keep packets closed, labelled and out of reach.
- Pregnant women. Ergometrine makes the muscle of the uterus contract (Wikipedia: Ergometrine).
- People with heart or blood pressure problems, because of the effects on blood vessels described above.
- People with a personal or family history of psychosis, given the psychiatric reactions in the case literature.
- People taking medication that acts on serotonin, dopamine or adrenaline receptors, which are the receptors these alkaloids bind to (Paulke et al., 2013).
Treated seed and the coating story
A story has circulated since the 1960s that seed companies coat morning glory seed with mercury or with something that makes people vomit, to discourage misuse. We looked for a primary source for it, such as a government notice, a journal article or a company statement, and found none. A news report from January 1965 describes calls in the medical press to restrict sales of the seeds and says the US Food and Drug Administration had "no immediate plans for federal controls"; it does not mention any coating (Science News Letter, 30 January 1965). We therefore regard the specific mercury story as unverified.
What is documented is that seed of many garden and farm plants is treated with fungicides or insecticides before sale, to protect it during germination. In the European Union, treated seed must say so: the label has to give the name of the product used, its active substances, safety phrases and any risk-reduction measures (Regulation (EC) No 1107/2009, Article 49). In the United States the federal labelling rule for treated seed covers agricultural and vegetable seed (7 CFR 201.31a); flower seed falls under state rules.
For a gardener this means two things. Read the packet and look for a statement that the seed is treated. And handle any seed packet as you would a garden chemical: wash your hands after sowing, and keep it away from food.
Pets
The ASPCA lists morning glory as toxic to dogs, cats and horses. It names lysergic acid, lysergamide, elymoclavine and chanoclavine as the toxic principles and vomiting as the main sign, with hallucinations possible after large amounts of seed (ASPCA).
If seeds have been swallowed
Contact a doctor or the poison information service in your country, or a vet for an animal, and say what plant it was. Call the emergency number straight away (112 in the EU, 999 in the UK, 911 in the US) if someone has chest pain, severe headache, cold or pale hands and feet, a seizure, or is confused or a danger to themselves.
Read on
- What is in the seeds
- Growing Heavenly Blue safely around children and pets
- Legal status of the seeds per country