Toxic effects occur with prolonged high intake. The specific toxicity is related to exposure time and the exposure concentration. A medical sign of chronic poisoning is the presence of painful tender swellings on the long bones. Anorexia, skin lesions, hair loss, hepatosplenomegaly, papilloedema, bleeding, general malaise, pseudotumor cerebri, and death may also occur. Chronic overdose also causes an increased lability of biological membranes and of the outer layer of the skin to peel. Recent research has suggested a role for<unk> s in cutaneous adverse effects for a variety of drugs including the antimalarial drug proguanil. It is proposed that drugs such as proguanil act to disrupt<unk>  homeostasis. Systemic<unk> s (isotretinoin, etretinate) are contraindicated during pregnancy as they may cause CNS, cranio-facial, cardiovascular and other defects.
Retinoid
Retinol
Epoetin beta
Vitamer
Immunoisolate
Β-Carotene
Phytosteroid
Psymberin