Immunosuppressant medicines after a transplant: principles, infection and sun risk

The immune system recognises a transplanted organ as foreign. Without treatment it would attack and damage it, which is rejection. Immunosuppressant medicines damp down that response. NHS Blood and Transplant states that people need these medicines to reduce the risk of the new kidney being rejected, and the same principle applies to other organs and to some bone-marrow and stem-cell transplants.

Teams usually use a combination, so that each drug can be used at a lower dose and side effects are shared out. The exact regimen varies with the organ, the centre, the time since the transplant and the person's own health, and changes over time.

NHS Blood and Transplant lists three common medicines after a kidney transplant and notes that it is not possible to list every side effect. Tacrolimus can impair kidney function at high levels, so blood levels are monitored, and it may raise blood sugar and cause tremor. Prednisolone, a steroid, can cause high blood pressure, increased appetite and thinned skin. Mycophenolate mofetil can cause nausea or diarrhoea and reduce white blood cell counts.

Azathioprine is an older alternative used after transplant and in other immune conditions. The NHS says to take it with or without food but not with milk or dairy products, to expect regular blood tests, and to take a missed dose as soon as you remember unless the next is close, telling the doctor if you miss two or more.

• Blood tests are routine, especially in the first weeks and months.

• Dose changes are made by the transplant team, not by the GP or pharmacy alone.

• Do not stop a drug because of a side effect without calling the team first.

A weakened immune response means infections can be more frequent, more severe or slower to show themselves. The NHS azathioprine pages advise avoiding close contact with people you know are unwell when possible, and advise telling the doctor about fever, sore throat or COVID-19 symptoms. They say to stop the medicine and call 111 for a high temperature with shivering or chills, cough or sore throat, which shows how seriously the symptoms are taken.

Keep your transplant centre's emergency contact details in your phone. Many centres want to hear about any fever, persistent diarrhoea, vomiting that stops medicines staying down, or a new rash early, because treatment and drug doses may need adjusting.

The NHS pages for azathioprine tell people to avoid strong sunlight, use sunscreen of SPF 30 or more and wear clothing covering arms and legs, because long-term use can increase the chance of certain cancers, including skin cancer. MedlinePlus also lists, among its references on transplant care, a review of photoaging and skin cancer in organ transplant recipients.

In practice, people on long-term immunosuppression are usually advised to check their skin regularly and have new, changing or non-healing spots looked at promptly. Many centres arrange dermatology follow-up. Our existing guide to skin cancer explains what to look for.

Immunosuppressants interact with many drugs. The NHS lists allopurinol, ciclosporin or tacrolimus, warfarin and chemotherapy drugs among those to mention for azathioprine, and says there is not enough information to say that herbal remedies, supplements or complementary medicines are safe with it. St John's wort, in particular, is well known to alter some transplant drug levels, so never add it without advice.

Always tell a pharmacist or prescriber that you are a transplant recipient, including for antibiotics, which can raise or lower levels. Before an operation, the NHS says to tell the doctor or anaesthetist. For vaccines, the NHS says it is important to have those you are invited for, but live vaccines are avoided and the live nasal flu vaccine is not used in children taking azathioprine.

Missing doses is the commonest preventable cause of late rejection, so build routines: a pill organiser, phone alarms, a travel supply, and a repeat-prescription calendar. Alcohol need not be forbidden, but the NHS notes both azathioprine and alcohol can strain the liver and suggests keeping within a stated weekly limit spread over several days.

Women and men who may become parents should discuss family planning with the team early, as some transplant drugs are unsuitable in pregnancy while others can be continued. The existing page on tacrolimus neurotoxicity covers one specific side effect in detail.