Mycophenolate (CellCept): immune-suppressing tablets, pregnancy rules and monitoring

Mycophenolate belongs to a group of medicines called immunosuppressants. Arthritis UK explains that it works by reducing the activity of the body’s immune system, which in inflammatory conditions may attack parts of the body such as the lungs, kidneys and blood vessels by mistake. Like other DMARDs, it slows how active the condition is rather than treating symptoms alone.

Two forms of the active substance are used. Mycophenolate mofetil is the one in CellCept and several generic products; mycophenolate sodium is a related form. Check the exact product name on your prescription and ask your pharmacist if it changes.

The CellCept leaflet says it is used to prevent the body rejecting a transplanted kidney, heart or liver in adults and children, together with ciclosporin and corticosteroids. NHS Blood and Transplant lists it among the common immunosuppressants after a kidney transplant, alongside tacrolimus and steroids, and notes side effects of diarrhoea or nausea and a reduced number of white cells in the blood.

Beyond transplants, Arthritis UK says mycophenolate is used to treat lupus and other connective tissue disorders including scleroderma, rheumatoid arthritis, psoriatic arthritis and conditions in which blood vessels are inflamed, such as vasculitis. It is sometimes also used as part of treatment of inflammatory eye conditions such as uveitis and of bowel conditions such as Crohn’s disease. In these uses it should help control the condition and reduce damage to joints and organs.

Arthritis UK says it may take up to four months before you notice benefit, and that it is important to keep taking it even if it does not seem to be working at first and when symptoms improve, as this helps control the condition.

It is usually started on one dose a day for the first week, rising to two doses a day as the medicine is increased, according to Arthritis UK, and taken with food and water to reduce sickness and stomach pains. Do not crush or chew the tablets or capsules. If you miss a dose take it as soon as you remember unless the next one is nearly due, and never take extra to make up.

This is the single most important safety topic. The CellCept leaflet opens its warning section by stating that mycophenolate causes birth defects and miscarriage. A woman who could become pregnant must provide a negative pregnancy test before starting and follow the contraception advice given. You should not take it if you are pregnant, planning pregnancy, think you may be pregnant, not using effective contraception, or breastfeeding.

Women who could become pregnant must use effective contraception before treatment, throughout treatment and for 6 weeks afterwards, and the leaflet says two forms are preferable. Arthritis UK gives the same advice, and says women are advised to wait six weeks after stopping before trying to conceive.

For men, the leaflet says the available evidence does not indicate an increased risk of malformations or miscarriage if the father takes mycophenolate, but a risk cannot be excluded, so reliable contraception is recommended during treatment and for 90 days afterwards. Arthritis UK advises men to wait 13 weeks before they stop using contraception. The leaflet also says not to donate blood during treatment and for at least 6 weeks afterwards, and that men must not donate semen during treatment and for at least 90 days afterwards.

Both sources say not to breastfeed on mycophenolate. If you are planning a family, talk to your specialist first; do not stop contraception or the medicine on your own.

Arthritis UK lists feeling sick, diarrhoea, vomiting and stomach pains as common. It asks you to tell your doctor, rheumatology nurse or pharmacist straight away about a sore throat, fever, flu-like symptoms, a constant cough or breathing problems, an unusual heartbeat, sudden weight loss, unexplained bruising or bleeding, unexplained mood changes, new headaches, acne or rash, swollen gums or an unusual taste in the mouth. If any of these is severe your doctor may advise stopping.

See your doctor as soon as possible if you come into contact with someone with shingles or chickenpox, or get them yourself, because these infections can affect you badly; you may need antiviral treatment, and mycophenolate may be stopped until you are better. Arthritis UK suggests avoiding close contact with people with infections, washing hands regularly, keeping your mouth clean, stopping smoking and preparing food safely.

There is a slightly increased risk of certain cancers, such as skin cancer, so wear sunscreen and check your skin for new spots or changes. Very rarely a serious brain condition called progressive multifocal leukoencephalopathy can occur, and symptoms such as pins and needles, weakness, unsteadiness, sight loss, speech problems or changes in behaviour need immediate medical attention. Mycophenolate can affect the blood count and sometimes cause liver or kidney problems, so blood tests are done before starting and regularly after.

If you take too much, call your team or NHS 111 for advice.

The CellCept leaflet lists azathioprine and other immune-suppressing medicines, cholestyramine, rifampicin, antacids and proton pump inhibitors, phosphate binders, some antibiotics, isavuconazole and telmisartan as medicines to mention. Arthritis UK says you can carry on taking NSAIDs and painkillers unless your doctor advises otherwise, but should not take over-the-counter or herbal remedies without discussing them first.

On vaccines, avoid live vaccines such as yellow fever, with exceptions agreed by your doctor. The shingles vaccine is not live and can be given; pneumococcal and yearly flu vaccines are recommended. On alcohol, Arthritis UK says mycophenolate and alcohol can both affect the liver, so drink only in small amounts, within the 14 units a week guideline, and some rheumatologists suggest stricter limits.

If you are going to have an operation, discuss with your team whether to continue before it.

Mycophenolate is prescribed and monitored by transplant, rheumatology, renal and other specialist teams in NHS hospitals, often with shared care. You should know when your blood tests are due and keep a record. Private specialists use the same monitoring and pregnancy-prevention rules.