The Markesh Dosh is one of the deadly and bad dosh of the astrological combinations of planets and constellations. It is such a bad effect that it tends to dissolve poison in the life of the person as well as his family members in whose birth chart it is formed. During the time of this dosh, there can be discomforts up to the level of death in the life of the person.
Markesh Dosh is created when the position of planets is so formed in the kundli (horoscope) that it possesses the power of deadly troubles or can result in death. Exalted lords of the 2nd and 7th house and debilitated Ascendant create this yoga in a kundli. Markesha yoga may increase a state of ill-being due to affliction or misfortune in ones life. Dwitiyesh and Saptamesh Dashas are also known to impose Markesh Yoga. In this period one has to bear intense unhappiness and sufferings. In some cases it may cause death of a person. In Marakesh yog or Marak period (killing period), accidental, un-natural and abnormal deaths are caused to the highest degree, especially when the sufficient and effective remedy is not performed.
Please remember that the remedies for Markesh need to be done with great devotion for them to be applicable. Also, it's best to do these remedies before the Markesh period otherwise the remedies may not be possible once the Markesh has become strong on you.