Many of us have heard that touching a toad will give you warts. Although this is not true, this saying is predominantly meant to deter young and inquisitive enthusiasts from interacting with toads for their safety. While not all toads can pose serious risks for amphibian lovers, some toads can be severely toxic to humans.
Few toad species are highly poisonous to humans including the Cane Toad and Colorado River Toad. Most toad species are only severely toxic to animals including cats and dogs. However, all toads can pose risks for young children and those with health vulnerabilities.
Toads may seem harmless compared to other toxic frog species, especially since some flaunt no external indicators to warn onlookers of their inherent toxicity levels. Join me as I discuss which toads are poisonous to humans and the effects of ingesting their toxins depending on the species.
All Toads Are Poisonous
All toads have poison-carrying parotoid glands located behind their eyes on the sides of their heads. However, these poisonous glands can also be housed inside numerous warts across the surface of their body. The toxic substance they release is generally thick, creamy, and white and generally has an unpleasant odor to warn predators in the wild.
These poisonous secretions generally hold one or more of the following toxins in varying degrees, depending on various factors such as the toad species and the level of maturity.
- Bufotoxin
- Bufotenin
- 5-MeO-DMT
- Bufotalin
- Bufalitoxin
The type of toxin toads release varies based on the toad species, making some toad species far more threatening than others. Every toad species utilizes a specific toxin or toxin blend as a primary defensive mechanism in the wild. These toxins are incredibly harmful to animals, including predators and household pets.
How Poisonous Are Toads to Humans?
While all toads are generally poisonous to animals, not all toads are toxic to humans. However, toxicity effects can also vary between cases, meaning that people may experience varying toxicity levels or side effects after poisoning.
The following factors generally influence the effect of ingesting toad toxins on people:
- The person’s age
- The person’s health status
- Prior health conditions
- The type of poison that was ingested
- The age and size of the toad (tadpole, toadlet, adult)
- How the person ingested the poison (blood, sinuses)
- How much poison was ingested
Below are examples of some common toad species, which toxins they carry, and how the effects of these toxins typically differ between animals and adult humans:
| Toad Species | Active Toxin | Toxic to Animals | Highly Toxic to Humans |
| Cane Toad | Bufotoxin Bufotenin | Yes | Yes |
| Colorado River Toad | 5-MeO-DMT Bufotenin | Yes | Yes |
| American Toad | Bufotoxin | Yes | No |
| Canadian Toad | Bufotoxin | Yes | No |
| Gulf Coast Toad | Bufotoxin | Yes | No |
| European Green Toad | Bufotoxin | Yes | No |
| Columbian Giant Toad | Bufotoxin | Yes | No |
| Fowler’s Toad | Bufotoxin | Yes | No |
| Western Toad | Bufotoxin | Yes | No |
| Oak Toad | Bufotoxin | Yes | No |
| Asian Giant Toad | Bufotoxin | Yes | No |
| Asiatic Toad | Bufotoxin | Yes | No |
| Asian Common Toad | Bufotoxin | Yes | No |
| African Common Toad | Bufotoxin | Yes | No |
| Common Toad | Bufotalin Bufalitoxin Bufotoxin | Yes | No |
| Japanese Common Toad | Bufatolin Bufotoxin | Yes | No |
Keep in mind that even if a toad is not highly toxic to adult humans, all amphibians including frogs and toads can carry viral or bacterial diseases on their skin and ingesting their secretions can have other health side effects. Also, all toads can still pose risks for young children and those with health vulnerabilities.
Toad tadpoles and juvenile toads, also known as toadlets, can also be toxic to humans as the specific toad species will carry the same active toxins as adults. Although the potency of these toxins will generally be lower based on a lessened amount of toxins held in their small bodies, it frequently aids their survival chances in the wild.
A lessened amount of toxins will still affect poisoned animals on a broad scale. As a result, this defensive mechanism often prevents the toad tadpoles and toadlets from being eaten by predators while they are still maturing.
Toad Poisoning Side Effects
The side effects of ingesting toad poison will generally depend on the toad species, ingested toxin, amount ingested, as well as the person’s age, pre-existing conditions and many other factors. Therefore, those affected should always seek medical attention as soon as possible.
Most toads are not highly toxic to humans or may only cause mild reactions, such as:
- Irritation
- Nausea
- Swelling
- Vomiting
However, a couple of toad species are extremely dangerous to humans irrespective of the person’s health status. The Colorado River Toad and the Cane Toad are highly toxic if their poisons are ingested. Both species secrete Bufotenin, which causes serious side effects in humans. Side effects of their poisoning can impact the affected person’s neurological, respiratory, musculoskeletal, and gastrointestinal systems.
The Cane Toad continues to rise in population and dominance throughout various locations worldwide, including (but not limited to) Australia, South America, Japan, and the USA in Florida. This highly toxic toad species is particularly dangerous, as its poison can be lethal in humans. Colorado River Toads are illegal to possess, and secrete 5-MeO-DMT, a toxin that can cause hallucinations and is known to kill humans in some cases.
| Toad Toxin | Properties | Possible Side Effects In Animals | Possible Side Effects In Humans |
| Bufotoxin | Steroid Lactones | Salivation, Head Shaking, Seizures, Vomiting, Collapsing, Cardiac Arrhythmia | Intoxication, Gastrointestinal issues, Abdominal Discomfort |
| Bufotenin | Alkaloid, Tryptamine Derivative | Cardiotoxicity, Vomiting, Diarrhea, Death | Psychedelic effects, Tightening in chest, Nausea, High Blood Pressure, Death in Some Cases |
| 5-MeO-DMT | Psychedelic Tryptamine Derivative | Nausea, Vomiting, Collapse, Death | Hallucinogenic, Death in Some Cases |
| Bufotalin | Cardiotoxic Steroid | Cardiotoxicity, Collapse, Death | Cardiac Effects, Increased Cancer Cells if Injected |
| Bufalitoxin | Steroid | Salivation, Head Shaking, Seizures, Vomiting, Collapsing, Cardiac Arrhythmia | Cardiac Effects, Gastrointestinal Issues |
Typical known side effects of toxic toad species differ between animals and humans. Above is an outline of the differences between how specific toad toxins may affect animals and humans.
When Do Toads Secrete Poison?
The use of toxic secretions greatly aids the survival chances of toads in the wild (CTNF). Toads generally reserve their poisonous secretions for instances where they feel threatened, including the following circumstances:
- When Squeezed: There are many reasons for toads secreting poison when they are squeezed, including the feeling of being in danger in addition to forced muscle contractions by the squeezing motion. These influences will result in the toad pushing out toxins to defend itself or as an uncontrollable reaction to being squeezed.
- When Afraid: Toads often release toxins when stressed, even if they are not physically threatened. Since humans are larger and stronger than toads, toads often identify inquisitive enthusiasts as a potential threat. They may fear for their lives and would secrete poison just in case.
- When Eaten: When toads are swallowed, they will secrete poison due to a combination of fear or anxiety and forced muscle contractions within the predator’s mouth. The poison will be used as a defensive survival tactic, and the toad may still have an opportunity to escape the predator’s mouth.
More About Frogs And Poison
Although some toad species can be extremely toxic to humans, most toads are primarily toxic to animals and will only cause mild poisoning in humans. Still, these toxins are a primary defensive mechanism for toads living in the wild, and curious amphibian lovers should always keep a safe distance when exploring toad habitats.
Learn more about poisonous toads and frogs on our blog:
