Does an allergy to penicillin run in the family?


Q. My son was recently prescribed a course of antibiotics for a throat infection. The doctor suggested penicillin, but my wife and two of her relatives are allergic to it, so I asked if he could be given something else, in case he was allergic, too. The doctor was rather dismissive of the idea that penicillin allergy runs in families. Does it?

A. Penicillin allergies can be unpleasant, occasionally serious, and, very rarely, fatal. The symptoms range from mild rashes to severe, life-threatening anaphylactic reactions. Even if someone has taken penicillin in the past, there is no guarantee that they will not become allergic to penicillin with a subsequent dose. But most people who think they are allergic to penicillin are not allergic to it. Research studies have shown that only about one in 10 people who claim to be penicillin allergic are correct. One reason for this is that, if someone taking penicillin develops a rash, they are often told to stop the medicine and consider themselves allergic to it, but the rash is more likely to have been caused by the illness than the penicillin. Penicillin allergy does not run in families, so if someone has a relative who is allergic to it, there is no reason to think that they will also be allergic to it.


Q. I am diabetic, and I'm going trekking in Tanzania. I need to have insulin injections several times a day. I understand that it may be possible to buy insulin in Dar es Salaam, but that it may not be easily available elsewhere. I usually keep my insulin in the fridge, but sometimes carry it around with me for a few days. How long can I keep it out of the fridge, before it goes off? Should I bring enough for the three-week trip, or get it locally?

A. You should definitely take enough insulin with you to last the whole trip. Although you may be able to get insulin in Tanzania, supplies are not reliable and you may not be able to get exactly the same type of insulin. Insulin can safely be kept out of the fridge for up to a month, although it must be kept below 30C (86F). I strongly recommend that you take syringes with you, and that you have a letter from a doctor stating that you are diabetic and need to carry insulin and syringes. Airport officials and border guards can be difficult, and an official letter sometimes helps.

Please send questions and suggestions to A Question of Health, 'The Independent', Independent House, 191 Marsh Wall, London E14 9RS; fax 020-7005 2182; e-mail Dr Kavalier regrets that he is unable to respond personally to questions.

Readers write

GM, from Hampshire, urges caution before embarking upon foot surgery:

Two years ago, I rushed into an operation to have a Morton's neuroma excised, on the assurance that I would feel the full benefit within six weeks. However, to my dismay, the nerve was badly upset by the surgery and there is still no sign of it healing, with the result that my foot is now far more painful than it was before the excision.