The patient’s tongue turned black and hairy (BMJ)

The tongue of a cancer patient turned black and hairy, likely as a result of a rare reaction to antibiotics used in her treatment doctors say.

The Japanese woman in her sixties was battling rectal cancer and had been undergoing chemotherapy for fourteen months following surgery. She had been taking the medication to counteract the side effects the treatment.

The affected area was described as a “brownish-black patch” with “prominent hair-like” growths and was said to be painful, the British Medical Journal reports.

As well as affecting her tongue the patient also developed grey skin on her face, doctors say.

Her treatment included the cancer drug panitumumab plus the antibiotic minocycline to prevent the panitumumab from causing skin lesions.

The woman was sent in for treatment for hepatitis B when she was diagnosed with drug-induced hyperpigmentation and a black hairy tongue (BHT).

BHT is a harmless condition often associated with poor oral hygeine.

However, the condition can also occur as a reaction to various drugs including a wide-range of antibiotics. Doctors concluded that the condition was most likely caused by minocycline.