Porphyria Cutanea Tarda (PCT)

2. Is PCT inherited?

Most patients have a form of PCT that is not inherited. This type of PCT is called sporadic or type I PCT. Most people with sporadic PCT recover well if the underlying risk factors are identified and treated, although regular follow-up is important because the condition can return.

In Europe, about one quarter of patients have an inherited risk factor for PCT – and have familial or type II PCT. This is caused by inheritance of a mutation which inactivates one copy of the UROD gene, leaving the other to function normally. Everyone has two genes for UROD in each cell in their body; one inherited from their mother and one from their father. Inactivation of one of the copies results in a reduction in UROD activity in every cell to about 50% of normal. However, most family members who inherit the gene mutation will not develop PCT because other causes (predisposing factors) need to be present as well, reducing the level of activity in the liver cells to about 20% of normal.

3. What are the most important predisposing factors?

The following are the most important predisposing factors that have been identified. Most patients will have at least one.

• Iron accumulation in the liver. Almost all PCT patients have an increase in iron in the liver, which is believed to be the most important factor involved in the inactivation of the UROD enzyme. Some of these patients may also have inherited a condition called haemochromatosis that is responsible for too much iron accumulating in the body.
• Regular alcohol consumption.
• Viral infections of the liver. Hepatitis C is an important predisposing factor for PCT in many European countries.
• Cigarette smoking
• Exposure to some industrial chemicals
• Oestrogen therapy. For example as oral contraception or hormone replacement therapy (HRT).
• Dialysis for kidney failure

4. What are the symptoms of PCT?

Only areas of the skin exposed to sunlight are affected. These are most commonly the backs of the hands, the face and scalp and any other areas of skin regularly exposed. Porphyrins circulating in the small blood vessels of the skin absorb energy from light. This triggers chemical reactions that damage the connection between the outermost layer of the skin (the epidermis) and the underlying layer (the dermis) leading to fragile skin. As a result, even minor knocks or everyday tasks may cause the skin to break or form large fluid filled blisters. These burst easily and heal slowly, often leaving scars and tiny white raised spots called milia. There may be changes in skin pigmentation, which can be increased or decreased, and an increased growth of fine hair on the cheeks and forehead. In addition to the skin problems, urine may take on a dark colour due to the large number of porphyrins being excreted. Unlike the acute porphyrias, PCT does not cause acute attacks with severe abdominal pain or nerve damage.

5. How is PCT diagnosed?

PCT is diagnosed by measuring porphyrins in samples of blood, urine and faeces. These tests look for the particular pattern of porphyrins associated with PCT. This is very important because other porphyrias can cause similar skin problems. Your doctor will usually also test for the predisposing factors described above which are associated with PCT. These will include blood tests for liver function, viral hepatitis, Human Immunodeficiency Virus (HIV), iron status and haemochromatosis. Because PCT can be associated with liver damage – due to alcohol, excess iron, hepatitis C virus or the porphyria itself – your doctor may order an ultrasound examination of your liver to look for scarring, too much fat in the liver or, rarely, liver cancer. Depending on the results of these tests, you may be advised to see another doctor, for example a liver specialist or haematologist. The porphyrin pattern in PCT is so characteristic that other tests to identify the type of porphyria are not normally required. Members of families in which there is more than one patient with PCT should be offered genetic counselling and may require screening for Type II PCT. If a genetic cause for iron overload is found, close relatives should be seen to determine whether they should be followed up or treated for iron overload.

6. Can PCT be cured?

PCT is one of the few porphyrias that can be treated very successfully. Although the underlying causes may not be curable, treatment can reduce porphyrin levels to normal allowing the skin problems to resolve. It is important that known predisposing factors are controlled or treated as well. With appropriate treatment, skin problems resolve slowly and eventually disappear, though they may leave some scars. Relapse two or more years after successful treatment may occur. This is why patients with PCT, whatever the contributing or predisposing factors are, should continue seeing their doctor regularly. For people whose PCT is associated with hepatitis C, modern direct-acting antiviral (DAA) medicines can cure the hepatitis C infection which usually  lead to resolution of the PCT. 

7. How can PCT be treated?

The aim of treatment is to remove or decrease any predisposing factors, to reverse the inactivation of UROD enzyme and to remove the excess porphyrin that has accumulated in the body. You are likely to be offered one of two specific treatments:

• Regular removal of blood (usually one unit every two weeks, which is the same amount as given by blood donors) to decrease iron levels. The medical term for this treatment is venesection. The body uses iron to make more blood and the process is repeated until enough iron has been removed – often 5 to 6 units of blood. This will take several months in most cases. If you also have haemochromatosis, venesection may be needed on a long-term basis. The lowering of liver iron concentrations results in improved function of UROD enzyme.
• Low-dose chloroquine or hydroxychloroquine (usually twice weekly tablet). It is important that only small doses are used, as larger doses can cause an acute illness. The chloroquine and hydroxychloroquine make the porphyrins more soluble and increase their excretion in the urine, which may result in some darkening of the urine. As only low doses of chloroquine or hydroxychloroquine are used, regular eye review is not generally required.

Both treatments are effective in most patients. The choice will depend on various factors, including which is the most important predisposing condition(s) in each patient. Occasionally both treatments may be required. In patients who cannot tolerate either treatment, other options, such as drugs that help remove iron from the body are available, although these are more complicated to administer. Other measures:

• Alcohol. Alcohol should be avoided, as it can increase porphyrin production and delay recovery.
• Cigarette smoking should be stopped.
• Oestrogen therapy. Women on oestrogen treatments will be asked to stop taking them while the PCT is being treated. However, once the PCT has been treated it may be possible to restart hormone treatment.
• Iron supplements should not be taken, unless you have clear evidence of iron deficiency.
• Treatment for hepatitis C. PCT in patients with hepatitis C may resolve with treatment with direct acting antiviral (DAA) drugs.

Occasionally skin symptoms may get worse and the urine can darken when treatment is started.

8. What can I do?

While treatment takes effect: Avoid sunlight and protect your skin from light exposure. The skin will remain fragile and sensitive to bright sunlight for several months until treatment becomes fully effective. The skin damage in PCT is caused by the visible part of the sun’s light spectrum, which means that ordinary sunscreens (which protect against ultraviolet light) do not work. Reflectant sunscreens based on titanium dioxide or zinc oxide cover will be more effective. Using a tanning cream containing dihydroxyacetone may block the light to some extent. You should avoid damaging the skin, by wearing protective clothing such as gloves (white cotton preferably), a hat (ideally brimmed or Foreign Legion-style), shoes rather than sandals, and minimising your exposure to the sun during this time. Wounds or broken blisters should be kept clean, and any skin infection treated promptly. Once treatment has reduced the porphyrin levels, most people are able to return to normal outdoor activities without developing new skin symptoms.

Reactions to other medications: PCT does not cause acute porphyria crises due to other medications. Unfortunately, some doctors and pharmacists confuse PCT with the “acute porphyrias” and may advise you to avoid certain medicines. In general, you can take whatever medicines your health requires. 

9. Where can I get more information about PCT?

As PCT is uncommon, most general practitioners will have little experience of the condition. However, dermatologists see most people with PCT and may sometimes ask for advice from a porphyria specialist centre. If you are concerned about the likelihood of passing the condition onto your children (familial PCT), you may be referred to a geneticist or porphyria specialist center for information.

The content on this website is based on a consensus agreed by Ipnet partners. Patient associations can be a good point of contact for information, networking and support. Porphyria organisations provide reliable information, practical advice and the opportunity to connect with other people living with PCT. See International Porphyria Network website and the Global Porphyria Advocacy Coalition (GPAC) website.

Revised June 2026