Uncooked yam is not toxic, but raw yam is not recommended for people with allergies or poor digestive function to avoid adverse effects.
Yams do not produce toxicity just because they are undercooked, but direct consumption of undercooked yams may cause discomfort and pose potential food safety risks. Uncooked yams may carry foodborne pathogens, such as microorganisms and parasites, which may cause foodborne illness.
Therefore, although yams do not have the property of causing poisoning when uncooked, it is recommended to cook them properly before consumption so as to reduce their potential food safety risk. Seek medical advice as soon as possible if you feel unwell.