The most common side effects individuals taking collagen capsules experience include hypercalcemia, bone pain, constipation, fatigue, abnormal heart rhythms and hypersensitivity to food or allergens, according to The Dermatology Review. Additionally, some individuals are allergic to collagen supplements.
Hypercalcemia is a condition that occurs when the body is overwhelmed with calcium, notes The Dermatology Review. Typically, it manifests itself through pain in the joints. Collagen is not recommended for individuals who tend to experience allergic reactions easily, since the proteins contained in collagen are animal-derived, and the body may not be used to their presence. Doctors recommend consulting with a specialist about the possible effects of collagen before taking a supplement.
Collagen supplements can reduce the need for pain medication in individuals who have osteoarthritis, according to WebMD. A typical oral program of collagen for this purpose is 1 gram twice daily for 10 weeks. Oral collagen supplements may not be effective at reducing joint pain induced by exercise, however. Additionally, individuals who take collagen supplements to treat dry or wrinkled skin may not necessarily see results. A 500 milligram dose of collagen taken orally twice daily over 12 weeks may improve skin conditions in women who have visibly aging skin.