Learn and Unlearn: Addressing Misinformation in Multilingual LLMs

TaiMing Lu, Philipp Koehn


Abstract
This paper investigates the propagation of information in multilingual large language models (LLMs) and evaluates the efficacy of various unlearning methods. We demonstrate that fake information, regardless of the language it is in, once introduced into these models through training data, can spread across different languages, compromising the integrity and reliability of the generated content. Our findings reveal that standard unlearning techniques, which typically focus on English data, are insufficient in mitigating the spread of harmful content in multilingual contexts and could inadvertently reinforce harmful content across languages. We show that only by addressing harmful responses in both English and the original language of the harmful data we can effectively eliminate it for all languages. This underscores the critical need for comprehensive unlearning strategies that consider the multilingual nature of modern LLMs to enhance their safety and reliability across landscapes.
Anthology ID:
2025.emnlp-main.516
Volume:
Proceedings of the 2025 Conference on Empirical Methods in Natural Language Processing
Month:
November
Year:
2025
Address:
Suzhou, China
Editors:
Christos Christodoulopoulos, Tanmoy Chakraborty, Carolyn Rose, Violet Peng
Venue:
EMNLP
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
10191–10206
Language:
URL:
https://preview.aclanthology.org/ingest-emnlp/2025.emnlp-main.516/
DOI:
Bibkey:
Cite (ACL):
TaiMing Lu and Philipp Koehn. 2025. Learn and Unlearn: Addressing Misinformation in Multilingual LLMs. In Proceedings of the 2025 Conference on Empirical Methods in Natural Language Processing, pages 10191–10206, Suzhou, China. Association for Computational Linguistics.
Cite (Informal):
Learn and Unlearn: Addressing Misinformation in Multilingual LLMs (Lu & Koehn, EMNLP 2025)
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https://preview.aclanthology.org/ingest-emnlp/2025.emnlp-main.516.pdf
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