There are no known side effects from using Nigella Sativa, Black Caraway seed.
Nigella is considered – GRAS, generally regarded as safe. It is highly valued as an idea complimentary therapy with conventional medicine.
Of course, too much of anything can be bad for anyone. Nigella has an oil on the seed shell that contains minute trace elements that can be toxic at high level of consumption.
Melanthin is toxic in large doses and nigelline is paralytic, use in moderation.
Nigella has been used as a cooking spice to 1000’s of years without incident. It has been recommended for daily use to stay healthy and ward off dangerous diseases.
Spice of life contains 1/4 teaspoon per capsule, only 600mg per capsule. Every person is different and the suggested amount to take relates to an average adult.
Users should vary the amount taken by the persons body weight, metabolism rate, sensitivity to aromatic herbs, etc.
In a very rare case, someone reported that they thought the spice had given them a headache. The fact that it is used as a migraine headache remedy would suggest some other cause. When in doubt, quit taking it and consult your health care provider.