There are mainly two types of Qust, Indian (Qust al Hindi) and Marine / Sea (Qust al Bahri)
Al-Qust Al-Bahri which is a white type of costus that was previously brought from India to the Arabian Peninsula in ships over the sea, which is why it was called sea costus)
An-Nawawi said: "Doctors unanimously agreed in their books that seafood increases urine and menstrual flow, is beneficial to poison, improves sexual desire, kills worms ... etc." As to whether it should be mixed with black seeds for the purpose you mentioned in the question, this case could only be decided by people who have experience in treating herbs.
There is another type of costus called the Indian costus that differs in some of the characteristics of the sea costus. Ibn Al-Qayyim said in Zaad Al-Ma'aad, "There are two types of costus: the white type called the sea costus and the Indian costus having the hottest nature among them, while the white type is the mildest. Both strokes have many advantages. "
Qust is warm and dry in the third degree and helps to dry out excess mucus, help relieve colds and flu and nasal congestion. Imam Ibn Al Qayyim said that drinking an infusion of Qust helps strengthen the liver and helps relieve digestive weakness, stomach weakness, and if used as an ointment, it relieves back pain or rheumatic pains in the lower back.
Sea / Marine Qust is slightly paler in color and also milder in taste and more suitable for administration to children