The Department of Health (DOH) said one should not self-medicate on Doxycycline, even those who waded through the floodwaters.

Doxycycline is a prophylaxis for water-borne diseases, especially leptospirosis, a serious infection from wading floodwaters contaminated with rat or animal urine.

However, DOH Spokesperson Assistant Secretary Albert Domingo said the recommended dosage for it would depend on their consulting physicians.

"Our advice is to consult a doctor, nurse, or health center. Antibiotics are not for self-medication," Domingo told reporters.

"The doctor or health worker will be the one to prescribe, this includes dosage," he added.

On Tuesday, DOH Secretary Ted Herbosa distributed free Doxycycline medicines to evacuation centers in Marikina.