How drugs leach out of your sweat (and can spoil your sofa)

A recent study revealed that various medicines can seep out of the body through sweat and body oils, potentially damaging leather furniture such as sofas. This occurs when drugs are distributed through different parts of the body and can be excreted in sweat and skin oil. Water-soluble drugs like aspirin and paracetamol usually accumulate in blood serum, while oil-soluble drugs like testosterone and ketamine tend to accumulate in organs and fat stores.

Most drugs are excreted through urine, with minimal amounts in faeces. When drugs diffuse from blood vessels into sweat ducts and sebaceous glands, they can lead to fading, cracking, or discoloration of leather furniture. A variety of drugs, including those for blood/heart conditions, arthritis, chemotherapy, diabetes, and even some vitamins, have been found in sweat.

Studies have also detected caffeine, nicotine, ketamine, and cocaine in sweat samples. Factors such as drug solubility, drug size, drug acidity, sweat pH, exercise levels, and environmental conditions can influence drug concentration in sweat. Although the amount of drug excreted through sweat is minimal and generally harmless, prolonged contact could potentially cause staining, discolouration, or damage to leather furniture.

However, formal studies on this topic have not been conducted. Retailers and sofa repairers have shared anecdotal reports about this issue. To minimize potential damage, it is advised to avoid sitting on the sofa if particularly sweaty or to protect it with a blanket or towel. Following the manufacturer's cleaning instructions is also recommended.