I have been having iodine-based dressings on a healing skin wound (I fell and cut myself badly). Now I seem to have eczema for the first time in my life, and I am over 70. Could this be a reaction to the iodine?

I'm afraid it could - iodine can, although thankfully rarely, cause a dermatitis that looks like eczema. Talk it over with your nurse, who may want to change the type of dressing, and discuss the problem with the doctor. The eczema may or may not disappear once the dressings are changed If it is a reaction to the iodine, steroid creams can help if it persists. But get these from your doctor, not over the counter.

I get palpitations after drinking coffee or when I'm a bit anxious. A friend says I should have a heart check. Is this true? How serious are palpitations?

Not serious at all in the majority of people. Most palpitations (runs of fast heartbeats) are caused by anxiety or coffee and other drinks containing caffeine, and are benign. You should see your doctor, who will take a detailed history, examine your heart, probably do a 12-lead ECG to rule out any abnormality, and reassure you. Other causes of palpitations include cigarette smoking, alcohol, slimming pills and thyroid overactivity, so you may need a thyroid function test, too. Be reassured. If you are one of the minority who does have a heart problem, then your GP will refer you on to a cardiologist, but even in cardiology clinics most 'palpitation patients' have no significant disease.

· Do you have a question for Dr Smith? Email doctordoctor@theguardian.com