Most psoriasis medications do not have established dosages for children. Care is advised when using salicylic acid on young children because they may be more likely to develop skin irritation. Because side effects may be worse in children, the use of psoriasis medications is typically closely monitored. Many medications (e.g., tazarotene, methoxsalen) are not recommended for use in children under the age of 12 years and others (e.g., acitretin) are only for use in adults. With long-term use, methotrexate may cause osteoporosis (loss of bone density) in children.