January 19, 2016

Symptoms of Mushroom Poisoning

Symptoms of Mushroom Poisoning

Many of the toxicity cases occur as a result of misidentification by amateur mushroom hunters or because small children ate them. There are thousands of species of mushrooms, but only about 100 species cause symptoms when eaten by humans, and only 15-20 are potentially lethal when ingested. There is no simple rule for distinguishing edible mushrooms from poisonous mushrooms. You need to learn to identify each and every mushroom that you eat.

Accidental poisonings tend to occur in the spring and fall when mushroom species are at the peak of their fruiting stage. In general, most ingestions result in minor GI illness, with only the most severe requiring medical attention. The US Poison Control reported that children under the age of 6 were more likely to eat a poisonous mushroom than older children, and the mushrooms were commonly raw morels, Chlorophyllum molybdites (false parasol), and Amanita muscaria, the fly agaric.

The mushrooms causing the most severe poisonings in adults are in the genus Amanita. They, and to a lesser extent the mushrooms in the genus Gyromitra, affect the liver. Some of the other toxins in poisonous mushrooms are central nervous system poisons, and still others target the liver and kidneys.

The toxicity of many wild mushrooms are still unknown. Some toxins vary with the environment, or concentrate heavy metals, which some of them do very well, or they are exposed to sprays or pesticides. The severity of poisoning also depends on the amount of toxin delivered. Cooking, freezing, or drying may not alter some toxins.

Some cases of mushroom poisoning involve people consuming popular edible mushrooms by using improper collection and storage methods. In one study most of the poisonings caused by edible mushrooms were because they were too old and stored in plastic.

Another problem is the poisonings of recent immigrants to North America. It seems that our poisonous mushrooms resemble edible mushrooms that were routinely picked in their native land. Since the 1970s Hmong immigrants from Laos have a higher rate than any other ethnic group with the genus Amanita being the most likely culprit. Other people from Southeast Asian have also fallen victim to Amanitas.

GI symptoms are the most frequently encountered due to mushroom toxins. Variations in symptoms may depend on an individual’s susceptibility and on the presence of other factors such as what else they might have eaten or drunk. Symptoms may show up right after the mushroom was eaten or may appear several hours later.

Early symptoms generally appear within the first 6 hours after ingestion that include nausea, stomach cramps, vomiting, and diarrhea, which can sometimes be bloody. Usually, mushrooms that produce symptoms within 2 hours are less dangerous than mushrooms that produce symptoms after 6 hours. Late symptoms begin to appear between 6-24 hours after ingestion and delayed symptoms appear more than 24 hours later.


The most frequent type of mushroom poisoning is caused by GI irritants. Symptoms can appear anywhere from 20 minutes to several hours later after ingesting the mushroom. They include nausea, diarrhea, stomach cramps, and vomiting. These symptoms usually pass once the irritant has left the body. Severe cases may need emergency medical care at a hospital. The body usually recovers rather quickly.


Some toxins can cause symptoms to begin in less than 30 minutes after eating the mushroom(s). They might include excessive salivation, sweating, severe diarrhea and vomiting. There may also be visual disturbances, an irregular pulse, low blood pressure, and breathing problems. Most people recover within 24 hours, but some people may experience more severe breathing problems and need emergency treatment.

More Severe Poisonings

If the symptoms begin 6 to 24 hours after eating the mushroom(s) it can be even more serious. Some of the toxins produced by the genus Amanita can cause serious liver and kidney damage. There are some cases where the onset of symptoms begin more than 24 hours, even up to a couple of weeks later, so it may be difficult to associate the symptoms with the prior ingestion of the mushroom(s).

Symptoms include diarrhea, vomiting, stomach cramps, sweating, and hot flashes. There may also be fever, an increased pulse, irregular heartbeat, low blood pressure, headaches, dizziness, vision disturbances, breathing problems, fatigue, loss of coordination, hallucinations, faintness, drowsiness, excessive thirst, and confusion, and even delirium, convulsions, and coma. Some of the toxins can be especially damaging to the liver and kidneys. If jaundice does occur this is very serious and you should get emergency medical care at once, if you haven’t already.

After the first onset of symptoms there can be 1-2 days remission and it appears that a full recovery will occur. Don’t ignored these initially symptoms; still seek treatment since symptoms can return creating more damage to the liver and/or kidneys. This is why it is important to take immediate action if any poisoning symptoms occur.

These same toxins, which may make adults sick, can be deadly to small children and pets. People bring home mushrooms, such as morels, and leave them in their collecting basket where they can be reached by children or their pet. Raw morels are poisonous as well as many other raw wild mushrooms. Be aware of mushrooms growing in areas where your children or pets play. Pick and dispose of them.

Toxins in the genus Cortinarius can be extremely serious. Symptoms can begin as long as three weeks after ingestion and include nausea, vomiting, lethargy, frequent urination, a burning thirst, headaches, feeling cold with shivering, anorexia, and kidney failure. Those with severe, but not irreversible damage may begin to recover kidney function in 2-4 weeks after the onset of symptoms.

There are mushrooms that release a product called mono-methyl-hydrazine (MMH), a colorless volatile, highly toxic, and carcinogenic compounds. MMH is used to make rocket fuel. Since this toxin is volatile, it has a low boiling point and can be inhaled. Usually it’s the person cooking the mushroom that will be poisoned. This toxin is in the genus Gyromitra and some species of Helvella, Verpa, and Cudonia.

If you suspect that you or someone else has ingested a poisonous mushroom, don’t wait for symptoms to appear. You will need to get to a hospital so that the toxins can be removed before being fully absorbed into the body. Learn to ID the poisonous mushrooms in your area from the ones that are edible so that you can tell the difference. It can save a life.

Hallucinogenic Mushrooms

These are mushrooms containing psilocybin and psilocin that can produce symptoms that begin within an hour after ingestion with the effects usually lasting 4-6 hours. The effect can be heightened color perception, emotional effects from ecstasy to anxiety, or even delusions. Some people have good trips and some people have very bad ones. A lot depends on the person’s emotional state and the amount eaten. Often, some toxic symptoms occur in the body prior to the psychological effects. They can include nausea and vomiting, shaking, and sometimes even a fever. This type of mushroom is more poisonous to small children, toddlers, and pets. They should be taken to a hospital immediately. But the most dangerous thing about hallucinogenic mushrooms is that they often grow near very deadly ones such as Galerina marginata, which is a little brown mushroom (LBM) that doesn’t look like it would be that dangerous.

Can Edible Mushrooms Cause Symptoms?

Occasionally, an edible mushroom can cause adverse symptoms in some sensitive individuals. That’s why it is important to always cook it properly and only eat a small amount of one species of mushroom when you sample a mushroom for the first time. Wait 24 hours before having any more to see if you are going to have a reaction.

Some people are just allergic or intolerant to some edible mushrooms even if cooked properly. It can even happen after eating a mushroom for years. I have a friend that ate Chlorophyllum rachodes without incident for 20 years and then became very sick after a meal of them. What might have caused such a reaction? Were they too old? Did he eat too many at one sitting? Did he have them several days in a row? Did he develop an allergy to them? The one thing he does know is that he won’t be eating them again.

Sometimes improper collection and storage methods have been used. Many people wait too long to eat a mushroom they have collected or bought at the market and then stored them in plastic bags or other plastic containers that don’t breathe. Also, if you collected your mushrooms when the weather was warm or hot and then carried them in plastic bags for more than 2-3 hours this can result in symptoms, not from mushroom toxins, but from food poisoning. The improper drying and storing of mushrooms can also produce toxic microorganisms that can make you sick.

Other factors can cause you to feel like you have been poisoned:

  • Eating too much at one time, especially the first time you eat that particular mushroom.
  • Having several servings of the same mushroom over a short period of time.
  • Under cooking the mushroom or eating it raw. Many wild mushrooms are poisonous raw, but harmless when cooked properly.
  • Some people just can’t digest mushrooms.
  • You have an allergy or an intolerance to mushrooms in general or to a particular one.
  • You inhaled mushrooms spores.

Who Do You Call?

Phone poison control, your doctor, or go to the local hospital. Call 911 immediately if the person is unconscious, not breathing or convulsing. It is important to have some of the mushroom that was eaten still available so that someone specializing in poisonous wild mushrooms can ID it. If you know anyone that is a mushroom expert that can ID that mushroom, you should make that phone call as soon as possible. That way the hospital will know more quickly what toxins are involved and be able to make a more effective treatment plan.

The National 24 hour Poison Action Line at 800-222-1222 is a free EMERGENCY identification service for people, but not just for mushroom poisoning. You will probably need to email a photo showing all sides of the mushroom. They usually don’t want photos taken with a cell phone since the resolution is too poor to allow accurate identification.

Go to the North American Mycological Association (www.namyco.org) and find the list of each state’s mushroom poisoning contacts, plus more details about mushroom poisonings. Once you are on their website go to “Poisonings” on the menu.

British Colombia Drug & Poison Information Centre at 800-567-8911.

What Else Should You Do?

You need to note the time from when the mushroom was ingested until symptoms began. Some symptoms of poisoning can take a long time to develop, even 1-2 days or more. It is important to keep a fresh mushroom in the refrigerator of any kind that you eat. Be sure to take the sample to the hospital or poison center with you so someone can ID it. If you did not keep a fresh sample, then you will need to keep an exact description of the mushroom or write down the genus or species name if you know it. You should also note whether or not alcohol was consumed around the same days that the mushroom was eaten. There are some mushrooms such as Coprinopsis atramentaria that can create some nasty symptoms when eaten in combination with alcohol within 72 hours before or after consumption.

Poisonings in Dogs and Cats

Our pets might eat a wild mushroom in their yard or while on a walk, or you left the raw morels lying out on the kitchen table, etc. Most mushrooms have little or no toxicity, but the ones that are poisonous can cause life-threatening problems. Keep your pets away from them or pick and dispose of any in your yard.

Dogs are more attracted to fishy-smelling mushrooms such as Amanita phalloides, A. pantherina, and A. muscaria, as well as Inocybe species. They are also attracted to mushrooms in the genus Scleroderma. Dogs are affected differently from humans when poisoned. Symptoms could include severe GI distress and refusal to eat or drink and then they go into a deep coma-like sleep a few hours later. They often recover, but it may be 6-72 hours later. Don’t let the vet euthanize your pet until you are able to see if they are going to recover. Giving atropine might make the situation worse. Cats rarely eat wild mushrooms, but they are attracted to dried Amanita muscaria and A. pantherina sometimes with lethal results. Not all mushrooms that are poisonous and even deadly to our pets are as poisonous to humans.

Try to get a sample of the same mushroom(s) from where they were found. This will help to identify it. Place the mushroom in a paper bag or waxed paper, not plastic, and refrigerate it until it can be examined. Make a note where the mushroom was collected just in case it has been contaminated by the uptake of toxins from pesticides or heavy metals from lawns, roadsides, or an industrial area.

See www.namyco.org for more information. If you suspect that your pet has eaten a poisonous mushroom, contact your veterinarian, pet emergency hospital, or the National 24 hour Poison Action Line at 800-222-1222, but there is a fee charged for calls about animals. The Animal Poison Control (ASPCA) 888-426-4435 is also a paid service.

Who Tracks Cases of Poisonings?

It is important to report any instances of poisoning even if you only had a GI upset or if it happened to your pet. Many toxins contained in wild mushrooms are poorly documented and have not been reported widely. The North American Mycological Association (NAMA) tracks this information at www.namyco.org. See the NAMA website for more information about poisonings and to file a written report of a poisoning case. Since NAMA maintains a case registry, this will help spread information about which wild mushrooms are causing problems.