Constipation is caused by irregular diet and lack of proper physical exercises.
To cure it in safe and natural ways use any one these recipes :

Recipe No.1:
Ginger juice : 2 spoon.
Honey : 2 spoon.
Castor Oil (Eranda oil) : 4 spoon
Mix all three and boil on SIM three times (till it boils up thrice).
Drink in war condition early in the morning.
Benefits:
Three to four motions take place and constipation is removed.

Recipe No.2:
Sonti (dry ginger) : 10 gm (fry and make powder)
Pippali (long pepper) powder: 20 gm
Pepper powder : 30 gm
Naaga kesaralu powder : 40 gm
Biryani leaf powder : 50 gm
Cinnamon powder : 60 gm
Elaichi (cardamom) powder : 70 gm
Candy sugar powder : 300 gm
Mix all ingradients and sive the powder. Store in a bottle.
Usage:
1/4th to 1 spoon along with honey and little warm water.
Benefits:
All stomach problems get cleared. bad water, gas will be eliminated, belly reduces, all waste products in the body are eliminated.

Recipe No.3:
Sonti (dry ginger) powder : 20 gm
Pepper powder : 20 gm
Lemon juice : 20 gm (4 tea spoons)
Sugar : 20 gms.
Usage :
Add all constitents in half glass warm water and drink.
Benefits:
Appetite improves, hunger increases, digestion improves, all the three doshas (Vaata, pitta, kapha) are eliminated