diff --git a/src/bluesearch/entrypoint/database/add.py b/src/bluesearch/entrypoint/database/add.py
index 7055f2941..ce7ea1e96 100644
--- a/src/bluesearch/entrypoint/database/add.py
+++ b/src/bluesearch/entrypoint/database/add.py
@@ -82,6 +82,7 @@ def run(
     import sqlalchemy
 
     from bluesearch.database.article import Article
+    from bluesearch.sql import retrieve_existing_article_ids
     from bluesearch.utils import load_spacy_model
 
     if db_type == "sqlite":
@@ -116,6 +117,13 @@ def run(
     if not articles:
         raise RuntimeWarning(f"No article was loaded from '{parsed_path}'!")
 
+    # Keep only articles not already present in the database
+    existing_uids = retrieve_existing_article_ids(engine)
+    articles = [article for article in articles if article.uid not in existing_uids]
+
+    if not articles:
+        raise RuntimeWarning(f"All articles are already saved in '{db_url}'!")
+
     logger.info("Loading spacy model")
     nlp = load_spacy_model("en_core_sci_lg", disable=["ner"])
 
diff --git a/src/bluesearch/sql.py b/src/bluesearch/sql.py
index 6b32018be..4a759250d 100644
--- a/src/bluesearch/sql.py
+++ b/src/bluesearch/sql.py
@@ -16,12 +16,14 @@
 #
 # You should have received a copy of the GNU Lesser General Public License
 # along with this program. If not, see <https://www.gnu.org/licenses/>.
+from __future__ import annotations
 
 import logging
 from typing import cast
 
 import numpy as np
 import pandas as pd
+import sqlalchemy
 import sqlalchemy.sql as sql
 
 
@@ -58,6 +60,24 @@ def get_titles(article_ids, engine):
     return titles
 
 
+def retrieve_existing_article_ids(engine: sqlalchemy.engine.Engine) -> list[str]:
+    """Retrieve all articles_ids from a database.
+
+    Parameters
+    ----------
+    engine : sqlalchemy.engine.Engine
+        SQLAlchemy Engine connected to the database.
+
+    Returns
+    -------
+    article_ids : list[str]
+        List of existing article_ids
+    """
+    result_proxy = engine.execute("SELECT article_id FROM articles")
+    article_ids = [result[0] for result in result_proxy.fetchall()]
+    return article_ids
+
+
 def retrieve_article_ids(engine):
     """Retrieve all articles_id from sentences table.
 
diff --git a/tests/unit/entrypoint/database/test_add.py b/tests/unit/entrypoint/database/test_add.py
index 306915250..a62cd5987 100644
--- a/tests/unit/entrypoint/database/test_add.py
+++ b/tests/unit/entrypoint/database/test_add.py
@@ -95,6 +95,16 @@ def test_sqlite_cord19(engine_sqlite, tmp_path, monkeypatch, model_entities):
     (n_rows_sentences,) = engine_sqlite.execute(query_sentences).fetchone()
     assert n_rows_sentences > 0
 
+    # Test adding something that is already in the database
+    with pytest.raises(RuntimeWarning):
+        args_and_opts = [
+            "add",
+            engine_sqlite.url.database,
+            str(parsed_dir),
+            "--db-type=sqlite",
+        ]
+        main(args_and_opts)
+
     # Test adding something that does not exist
     with pytest.raises(ValueError):
         args_and_opts = [
diff --git a/tests/unit/test_sql.py b/tests/unit/test_sql.py
index 71a5a93f6..45f7eb027 100644
--- a/tests/unit/test_sql.py
+++ b/tests/unit/test_sql.py
@@ -30,6 +30,7 @@
     retrieve_article_ids,
     retrieve_article_metadata_from_article_id,
     retrieve_articles,
+    retrieve_existing_article_ids,
     retrieve_mining_cache,
     retrieve_paragraph,
     retrieve_paragraph_from_sentence_id,
@@ -182,6 +183,13 @@ def test_retrieve_article(
                 == len(set(article_id)) * test_parameters["n_sections_per_article"]
             )
 
+    def test_retrieve_existing_article_ids(
+        self, fake_sqlalchemy_engine, test_parameters
+    ):
+        article_ids = retrieve_existing_article_ids(fake_sqlalchemy_engine)
+        assert isinstance(article_ids, list)
+        assert len(article_ids) == test_parameters["n_articles"]
+
     def test_retrieve_articles_ids(self, fake_sqlalchemy_engine, test_parameters):
         article_ids_dict = retrieve_article_ids(fake_sqlalchemy_engine)
         assert isinstance(article_ids_dict, dict)