Heat or allergic reaction to antimalarials?

Patient: I have been in south east Asia for two months, taking 100mg of doxycycline daily for antimalarials. After around two weeks I noticed lots of small white head spots on my shoulders. They do not burst or pop like a pimple. They can be sore and sometimes itchy. They are very unsightly. They have spread to my jaw line also and I have had some on my chest and the tops of my arms. I don’t know if it is a reaction to the doxy or the heat, humidity and dust or even suncream. I had a similar reaction 4 years ago whilst visiting the same countries, it cleared up once I was home but I never knew what caused it. I showed a pharmacist in Cambodia he had poor English and all he could suggest was antihistamine.

Symptoms: Spots, rash

Doctor: Such eruptions are unlikely due to allergy. They are commonly seen due to heat and can be easily managed by local applic ation of lacto-calamine lotion. In some cases, due to persistent itching, folliculitis (infection/inflammation of the hair follicles) may cause pain. Your dermatologist may prescribe you a course of antibiotics to resolve such infection.