Genentech has added a warning to the label for its psoriasis drug, Raptiva (efalizumab), to highlight an increased risk of developing a certain type of anaemia.

In a “Dear Doctor” letter, the US biotechnology company said that two cases of haemolytic anaemia were observed in Raptiva clinical trials and two further cases were reported after the drug won approval. Although the company says that a causal relationship has not been established, it cannot be excluded.

Serious infections, such as bacterial sepsis and severe pneumonia have also been linked to Raptiva treatment, and are also included on the label.