Castor Oil

Uses:

• Especially useful in case of constipation, rheumatic fever.
• Useful in pain of heart, bladder, sides of chest, knee joint, thigh, waist, back and bone.¹
• It is also useful in flatulence, tumor in abdomen, gout, splenic disorder, asthma etc.¹

A Variety of Castor Oil:

• Oil derived from red variety of castor - is extremely sharp and hot. It also is excessively pitta aggravating.¹

Castor oil pack for abdominal pain and cramps during menstruation: 

• Warm 3 tablespoon of castor oil.
• Pour this into a soft cloth (like a handkerchief).
• Make sure to spread the oil evenly.
• Place this on your lower abdomen.
• You can also place hot water bottle on top of this pack. 
• This pack will also provide relief in case of discomfort caused by endometriosis.

References:

Primary Source: Archarya Balkrishna - 

1. Vaidya Bhagwan Dash, Vaidya Lalitesh Kashyap - Materia Medica of Ayurveda