The reason men and women experience disease and react to drugs differently is more complex than we think, according to a new study in mice.

Until now, it tended to be assumed that the differences could be put down to body weight, with women being thought of as smaller versions of men in terms of physiology.

However, scientists at the University of New South Wales, and the European Bioinformatics Institute, UK, found that body weight alone was not sufficient to account for sex differences in many areas, such as fat mass and iron levels.

In reality, while females are generally smaller than males, their body and organ traits do not scale proportionally to this weight difference.

This is important when considering that women can experience up to 75% more adverse reactions to drugs than men – and highlights that simply adjusting drug doses based on body weight may not be enough to alleviate symptoms and reduce health risks.

Two of the authors wrote in an article published in The Conversation: “In an era where personalised medicine interventions are within reach, and patient-specific solutions are on the horizon, we now know that sex-based data are much needed to advance care in an equitable and effective manner.”

See also a recent study by EARA member the Max Planck Institute for Biology of Ageing, Germany, and University College London, UK, on the different effects of an anti-ageing drug on male and female fruit flies.

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