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Itchy Skin With No Rash: What Unexplained Itching All Over the Body Can Mean and Which Blood Tests Find the Cause

Itching all over with no rash often comes from dry skin or a medicine, but it can also come from low iron, the liver, the kidneys, the thyroid, blood sugar or, rarely, a blood disorder. Learn which blood tests check each cause, how ferritin, bilirubin, ALP, creatinine, eGFR, TSH, A1C and a blood count point to it, what all-normal results mean, and when to get prompt care.

Published

November 13, 2026

Read time

14 min read

Medically reviewed by

Rhonda Collins, FNP-C

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Itching all over the body with no rash often comes from dry skin or a reaction to a medicine. Less often it is a sign of something inside the body: low iron, liver or bile flow problems, kidney disease, a thyroid problem, high blood sugar or, rarely, a blood disorder such as polycythemia vera or lymphoma ^[1][2][3].

A first round of blood tests checks for most of these causes at once. Guidelines for itch without a rash start with a complete blood count with differential, ferritin, a liver panel with bilirubin and alkaline phosphatase (ALP), creatinine, a thyroid test (TSH) and a blood sugar test such as hemoglobin A1C ^[2][3][4]. If those are normal, a serious internal cause is less likely, although up to half of people with itch all over never get a clear cause ^[3]. Itch that is severe, lasts or comes with yellow eyes, night sweats or weight loss needs prompt attention ^[1][5].

Itch without a rash vs itch that starts with a rash

The most useful question about any itch is how the skin looked when the itch first started. Itch that began on normal-looking skin points away from a skin disease and toward a whole-body cause, a nerve problem or a medicine ^[2].

Skin diseases such as eczema and psoriasis cause most chronic itch. In a 2024 review in JAMA, inflammation in the skin explained about 60% of chronic itch, nerve-related causes about 25%, and about 15% came from other causes, including whole-body diseases and medicines ^[4]. Chronic itch is itch that lasts 6 weeks or longer ^[4].

Scratching itself can leave marks, scabs and thickened patches. Those marks do not count as a rash in this sense, because they came after the itch rather than before it ^[2].

Common outside causes: dry skin, medicines and nerves

Dry skin is a common cause of itching with no visible rash, and it is especially common in older adults in winter ^[1][3].

Dry skin can be subtle, showing only fine scale on close inspection ^[3]. Itch that flares as the skin cools after a warm shower can come from dry skin as well as from the blood causes covered below ^[2].

• Medicines. Almost any medicine can cause itch, and itch with no visible skin change accounts for about 5% of skin reactions to medicines ^[2]. Some medicines cause itch by slowing bile flow from the liver ^[2][6]. The only way to know is a supervised trial off the medicine, if that is possible, so do not stop a prescribed medicine without talking to the prescriber ^[3].
• Nerves. Itch from irritated or damaged nerves often comes with tingling, burning, prickling or numbness. It is usually in one area, such as one patch of the upper back or the outer forearms, rather than all over ^[2][3].
• Pregnancy. Pregnancy is one of the listed causes of itching all over the body, and liver-related itch can start in pregnancy, so tell your prenatal provider about it ^[1][6].

Low iron and ferritin

Iron deficiency is one of the internal causes of itching all over. MedlinePlus lists iron deficiency anemia among the causes of generalized itching, and guidelines put ferritin in the first round of blood tests for itch without a rash ^[1][2][3].

Ferritin is the protein that stores iron, and a ferritin test shows how much iron the body has stored ^[7]. Iron deficiency anemia develops only when the body’s iron stores run low ^[8]. That means a normal hemoglobin does not rule out low iron. The European guideline lists iron deficiency itself, not only anemia, among the causes of chronic itch ^[2].

Ferritin has one catch. It also rises with inflammation, so a normal ferritin can hide low iron. Dermatology guidance advises checking serum iron and total iron-binding capacity (TIBC) when low iron is suspected but ferritin looks normal ^[3]. Unexplained low iron is also a reason to test for celiac disease ^[3].

Iron overload can cause itch too. The European guideline lists hemochromatosis among the causes of chronic itch ^[2]. See hemochromatosis symptoms and blood tests and low ferritin symptoms.

At Mito, the ferritin test measures iron stores, and the iron and TIBC test adds serum iron and iron-binding capacity.

Liver and bile flow: bilirubin and ALP

Itch is a common sign of cholestasis, the slowing or blocking of bile flow from the liver. On blood tests, cholestasis usually shows up as a raised bilirubin and alkaline phosphatase (ALP) ^[6].

Liver-related itch does not need yellow skin. The European guideline notes that cholestasis and jaundice are not required for itch from liver and bile duct disease, and that this itch can come years before a diagnosis such as primary biliary cholangitis (PBC) ^[2]. It is usually worst in the evening and at night, and it often affects the palms and soles ^[2].

Cholestasis has causes inside and outside the liver. They include gallstones in the bile duct, narrowed bile ducts, hepatitis, alcohol-related liver disease, PBC, primary sclerosing cholangitis, pregnancy and some medicines ^[6]. Itch is less common in viral or alcohol-related liver disease than in PBC and sclerosing cholangitis ^[2].

Watch for the signs that travel with it. Cholestasis can also cause pale or clay-colored stools, dark urine and yellow skin or eyes ^[6]. Each has its own page: yellow eyes, pale stool and dark urine. For the wider picture, see liver disease symptoms and blood tests.

Kidney disease: creatinine and eGFR

Chronic kidney disease can cause daily or near-daily itching without a skin cause. It usually appears once kidney disease is advanced, because early kidney disease rarely causes symptoms ^[9][10].

The NIDDK lists itching, numbness and dry skin among the symptoms of more advanced kidney disease ^[10]. Kidney-related itch is common in people on dialysis: more than 40% of people on hemodialysis have chronic itch ^[9]. It is often felt on the back ^[2]. Other causes such as liver and thyroid disease are ruled out before itch is blamed on the kidneys ^[9].

Two blood numbers check the kidneys. Creatinine is a waste product that builds up when the kidneys filter poorly, and labs use it to calculate eGFR, the estimated filtering rate ^[11]. MedlinePlus describes an eGFR between 60 and 90 as possible early kidney disease, between 15 and 60 as possible kidney disease, and below 15 as possible kidney failure ^[11]. There is no creatinine cutoff above which itch is known to come from the kidneys ^[2]. See kidney disease symptoms and blood tests.

Thyroid: TSH

Both an overactive and an underactive thyroid can cause itch, though fewer than 10% of people with thyroid disease report it ^[2]. MedlinePlus lists itchy skin among the symptoms of hyperthyroidism ^[12]. In hypothyroidism, the itch probably comes from dry skin ^[2].

TSH is the first thyroid test for itch ^[2]. A high TSH usually means the thyroid is underactive, and a low TSH usually means it is overactive ^[13]. TSH can be off for other reasons, including serious illness, pregnancy and age over 80 ^[13]. At Mito, the TSH test checks it on its own.

An overactive parathyroid gland is a separate cause of itch that a calcium level on a metabolic panel can flag ^[2]. See hyperparathyroidism symptoms and blood tests.

Blood sugar: A1C

Diabetes is a less common cause of itching all over. Fewer than 10% of people with diabetes report itch, often because of dry skin, and diabetes is the leading cause of the small-nerve damage that can make skin itch ^[2]. Itch from diabetes can also be localized, such as genital itch ^[2].

The European guideline includes hemoglobin A1C and fasting glucose in its first round of tests ^[2]. MedlinePlus gives these A1C ranges: below 5.7% is normal, 5.7% to 6.4% is prediabetes, and 6.5% or higher is diabetes ^[14]. Anemia, kidney failure and liver disease can make A1C less accurate, which matters because each of them can also cause itch ^[14]. The hemoglobin A1C test measures it at Mito.

Polycythemia vera and lymphoma

Two blood disorders can cause itch without a rash: polycythemia vera, which makes too many red blood cells, and lymphoma. Both are rare causes, and a blood count is the first check for each ^[3][15][5].

Polycythemia vera (PV). PV is a rare bone marrow disorder that is not usually seen before age 40 ^[15]. One of its symptoms is itching, especially after a warm bath ^[15]. Dermatology guidance says PV should be considered when hemoglobin or hematocrit is raised, especially with a raised white cell or platelet count ^[3]. Itch triggered by water can come before PV by about 5 years, so people with it are advised to have a yearly blood count ^[3]. See high hemoglobin symptoms.

Hodgkin lymphoma. MedlinePlus lists itching all over the body that cannot be explained among its symptoms ^[5]. The itch often starts on the legs and is worst at night ^[2]. Night-time itch all over together with chills, fatigue, fever, drenching night sweats or weight loss is the pattern that suggests lymphoma ^[2][5]. A blood count and chemistry tests are part of the workup, but lymphoma is diagnosed with a biopsy ^[5]. See does lymphoma show up in blood work.

Autoimmune causes of itching

The autoimmune disease most tied to itch without a rash is primary biliary cholangitis (PBC). In PBC, the immune system attacks the small bile ducts in the liver, and the most common symptoms are tiredness and itchy skin ^[16].

Many people with PBC have no symptoms at first and are found through blood tests ^[16]. PBC most often affects middle-aged women ^[17]. ALP is the most important liver test for it, and an anti-mitochondrial antibody test is positive in about 95% of cases ^[17].

Other autoimmune conditions can cause itch too. In Sjögren syndrome, itch usually comes with very dry skin ^[2]. Celiac disease is worth testing for when iron is low without a clear reason ^[3]. PBC is also linked with thyroid disease and celiac disease ^[17].

Itching at night and all over the body

Where and when the itch happens gives the clues that point to a cause. Constant itch is typical of internal causes such as kidney disease, liver disease and lymphoma ^[2].

Which blood tests to get for itching without a rash

Dermatology guidelines agree on a first round of blood tests for itch all over with no skin cause: a blood count with differential, ferritin, kidney tests, liver tests and a thyroid test. The European guideline adds A1C and fasting glucose ^[2][3][4].

At Mito, the comprehensive metabolic panel (CMP) covers the chemistry in one draw: total bilirubin, ALP, ALT, AST, albumin, creatinine, urea nitrogen, calcium and glucose. A complete blood count with differential adds hemoglobin, hematocrit, platelets and each white cell type. For a fuller liver read, the hepatic function panel adds direct bilirubin. Mito Core covers the CMP markers, a complete blood count with differential, ferritin, iron, TSH and A1C together.

Some tests depend on what the first round shows. A clinician may add an anti-mitochondrial antibody test for PBC, hepatitis or HIV tests, a chest x-ray or imaging ^[2][3].

Reading the result patterns

No single number proves why skin itches. The pattern across tests narrows the cause, and the first round mainly decides which follow-up tests are worth doing ^[2][3].

• Low ferritin, normal hemoglobin. Iron stores are low before anemia has developed ^[7][8]. This still counts as iron deficiency ^[2].
• Low hemoglobin with small red cells. This suggests iron deficiency anemia. If ferritin is normal, serum iron and TIBC come next, because inflammation can raise ferritin ^[3].
• High hemoglobin or hematocrit, especially with high white cells or platelets. This raises the question of polycythemia vera and calls for a referral to a blood specialist ^[3].
• High eosinophils. Eosinophils fight parasites and take part in allergies ^[18]. After foreign travel, a high count raises the question of a parasite ^[3]. See high eosinophils.
• High ALP and bilirubin. This is the pattern of slowed bile flow ^[6]. A raised GGT along with a raised ALP points to the liver rather than bone ^[19]. See high ALP.
• High creatinine, low eGFR. This suggests reduced kidney filtering ^[11]. See low eGFR.
• Abnormal TSH. A thyroid problem is possible, and free T4 and thyroid antibodies are the usual next tests ^[2][13].
• A1C of 5.7% or higher. This points to prediabetes or diabetes ^[14]. See high A1C.

What all-normal results mean

Normal first-round blood tests make a serious internal cause of itch less likely. Dermatology guidance says healthy people with normal screening blood tests do not usually need detailed tests for an internal cancer ^[3].

Many people never get a single explanation. Up to 50% of people with itch all over have no clear cause, which is called idiopathic itch ^[3]. When no whole-body disease is found, the itch is likely to be nerve-related or of unknown origin ^[4]. Dry skin and medicines remain worth a second look.

Normal results are not permanent. Itch can come before the disease behind it, sometimes by years ^[2]. Guidance suggests repeating the blood count when itch stays severe with no cause, and considering scans for new, severe itch that started within the last three months ^[3].

When to get prompt care for itching without a rash

MedlinePlus advises having itch checked as soon as possible when it keeps coming back with no clear cause, or when you itch all over your body. Contact your provider for itch that is severe, does not go away or cannot be explained ^[1].

Get care promptly when itch comes with:

• yellow skin or eyes, dark urine or pale stools, which can mean blocked bile flow ^[6];
• drenching night sweats, fever, weight loss you cannot explain or a painless swollen lymph node, which can be signs of lymphoma ^[5];
• new, severe itch all over that started within the last three months ^[3];
• itch during pregnancy ^[1][6].

Itch on its own, with normal blood tests and no other symptoms, can usually be followed up with your regular provider ^[1][3].

References

1. MedlinePlus. Itching. National Library of Medicine. Reviewed August 5, 2024.
2. Weisshaar E, Müller S, Szepietowski JC, et al. European S2k guideline on chronic pruritus. Acta Derm Venereol. 2025;105:adv44220. PMID: 40843597
3. Primary Care Dermatology Society. Pruritus (itch) without a rash. Last updated June 16, 2026.
4. Butler DC, Berger T, Elmariah S, et al. Chronic pruritus: a review. JAMA. 2024;331(24):2114-2124. PMID: 38809527
5. MedlinePlus. Hodgkin lymphoma. National Library of Medicine. Reviewed February 3, 2025.
6. MedlinePlus. Cholestasis. National Library of Medicine. Reviewed April 27, 2026.
7. MedlinePlus. Ferritin blood test. National Library of Medicine. Last updated March 18, 2025.
8. MedlinePlus. Iron deficiency anemia. National Library of Medicine. Reviewed April 1, 2025.
9. Osakwe N, Rout P. Uremic pruritus evaluation and treatment. In: StatPearls. StatPearls Publishing; 2024. PMID: 36508514
10. National Institute of Diabetes and Digestive and Kidney Diseases. What is chronic kidney disease? Last reviewed February 2025.
11. MedlinePlus. Estimated glomerular filtration rate (eGFR) test. National Library of Medicine. Last updated September 30, 2026.
12. MedlinePlus. Hyperthyroidism. National Library of Medicine. Reviewed August 19, 2026.
13. MedlinePlus. TSH (thyroid-stimulating hormone) test. National Library of Medicine. Last updated October 30, 2024.
14. MedlinePlus. Hemoglobin A1C (HbA1c) test. National Library of Medicine. Last updated May 20, 2025.
15. MedlinePlus. Polycythemia vera. National Library of Medicine. Reviewed February 3, 2025.
16. National Institute of Diabetes and Digestive and Kidney Diseases. Symptoms & causes of primary biliary cholangitis. Last reviewed March 2021.
17. MedlinePlus. Primary biliary cholangitis. National Library of Medicine. Reviewed April 27, 2026.
18. MedlinePlus. Blood differential. National Library of Medicine. Last updated October 9, 2024.
19. MedlinePlus. Gamma-glutamyl transferase (GGT) test. National Library of Medicine. Last updated July 29, 2024.

Frequently asked questions

Can a vitamin or mineral deficiency cause itching all over the body?

Iron deficiency is the deficiency most clearly linked to itch. MedlinePlus lists iron deficiency anemia among the causes of itching all over the body, and the European guideline on chronic itch lists iron deficiency among the systemic causes and puts ferritin in its first round of blood tests. Anemia only develops once the body has run its iron stores low, so a ferritin test, which measures those stores, is the useful check. A normal hemoglobin on its own does not rule low iron out.

Can an autoimmune disease cause itching without a rash?

Yes. Primary biliary cholangitis, an autoimmune disease in which the immune system attacks the small bile ducts in the liver, most often shows up as tiredness and itchy skin, and the itch can come years before the diagnosis. A raised alkaline phosphatase (ALP) on a liver panel is the key blood clue, and an anti-mitochondrial antibody test helps confirm it. Sjögren syndrome can also cause itch, usually through very dry skin, and unexplained iron deficiency can be a sign of celiac disease.

Does kidney disease cause itching?

It can, usually once kidney disease is advanced. The NIDDK lists itching and dry skin among the symptoms of more advanced chronic kidney disease, while early kidney disease usually causes no symptoms. Kidney-related itch is daily or near-daily itching without a skin cause, and other causes such as liver and thyroid disease are ruled out first. Creatinine and eGFR are the blood tests that check how well the kidneys filter.

What does Hodgkin lymphoma itching feel like?

Hodgkin lymphoma can cause itching all over the body that cannot be explained. The European guideline on chronic itch describes it as often starting on the legs, being worst at night and then spreading. Itch is a concern alongside other signs such as a painless swollen lymph node, drenching night sweats, fever or weight loss that cannot be explained. Lymphoma is a rare cause of itch, and it is diagnosed with a biopsy, not a blood test, so these signs need a prompt clinician visit.

Which infection causes itching all over the body?

Hepatitis is the infection MedlinePlus lists among the causes of itching all over the body, and itch has been reported in up to 15 percent of people with chronic hepatitis C. The European guideline also notes that HIV can cause chronic itch, sometimes as its first sign, and that parasites can cause itch, especially when a blood count shows raised eosinophils after travel. Testing for these infections is ordered based on symptoms and risk.