Using a special mouthwash for a week killed some good bacteria in the mouth, which made less nitrite in saliva and blood, and this caused blood pressure to go up a little bit.

Good bacteria in the mouth turn nitrate into nitrite, and when you kill these bacteria with mouthwash, this conversion stops almost completely.

Using mouthwash that kills bacteria in the mouth makes it harder for the body to convert nitrate to nitrite, which lowers nitrite levels in the blood.

When bacteria that help convert nitrate to nitrite in the mouth are reduced, blood pressure tends to go up by a small amount (2-3.5 mmHg for systolic and 2-2.2 mmHg for diastolic).

When nitrite levels in the blood went down after using mouthwash, blood pressure went up, and this connection was strong enough to be statistically significant.

Using a common antibacterial mouthwash for a week can lower nitrite levels in saliva, which might make it easier for tooth decay to develop.