Vitamin B7 (Biotin) is a B vitamin that dissolves in water. It is also called vitamin B7, vitamin H or coenzyme R. Your body needs small amounts of it every day to turn the fats, carbohydrates and proteins in food into energy. Most people get enough from foods such as eggs, meat, fish, seeds, nuts and some vegetables. Doctors may advise Vitamin B7 (Biotin) supplements for people with a low level of it in the body. This includes people with biotinidase deficiency, a rare inherited condition in which the body cannot reuse and release this vitamin properly. Vitamin B7 (Biotin) comes as tablets and capsules, either alone or as part of B-complex and multivitamin products.

Vitamin B7 (Biotin) is one of the eight B vitamins. It dissolves in water, so the body does not store large amounts of it. Your body uses it as a helper molecule, called a coenzyme, for a small group of enzymes known as carboxylases. These enzymes help break down fats, sugars and some amino acids (the building blocks of protein). They also help the body build new fats. Vitamin B7 (Biotin) also seems to play a part in how cells control their genes and send signals to each other.

Most people who eat a varied diet get enough Vitamin B7 (Biotin), so true deficiency is uncommon. When it does happen, signs can include:

• thinning hair or hair loss
• a red, scaly rash around the eyes, nose and mouth
• brittle nails
• pink eye (conjunctivitis)
• low mood and tiredness
• hallucinations
• numbness or tingling in the hands and feet

Doctors use Vitamin B7 (Biotin) for the following reasons:

• Low biotin levels (biotin deficiency): Vitamin B7 (Biotin) can treat or prevent low levels. Causes include long-term heavy alcohol use, taking certain seizure medicines for a long time, and regularly eating raw egg whites. Mild deficiency can also develop during pregnancy.
• Biotinidase deficiency: This inherited condition needs lifelong treatment. In babies who are not treated, it can cause seizures, weak muscle tone, breathing problems, skin rash, hair loss, hearing or vision loss, and delayed development.
• Holocarboxylase synthetase deficiency: This is another rare inherited condition that affects how the body uses Vitamin B7 (Biotin). A specialist manages the treatment.
• Nutritional support: Vitamin B7 (Biotin) is included in B-complex and multivitamin products to help meet daily needs.

Vitamin B7 (Biotin) supplements are widely sold for hair, skin and nails. However, they are not an established treatment for hair loss or brittle nails in people whose biotin levels are normal.

One key safety point applies to everyone. High doses of Vitamin B7 (Biotin) can affect some laboratory blood tests and make the results falsely high or falsely low. These include heart attack tests (troponin) and thyroid tests. A wrong result could lead to a missed or wrong diagnosis. Always tell your doctor and the laboratory staff if you take Vitamin B7 (Biotin), including in hair, skin and nail supplements.

1. Treats and prevents deficiency: Vitamin B7 (Biotin) replaces the vitamin in people whose diet, medicines or health conditions leave them with too little of it.
2. Essential treatment for biotinidase deficiency: Lifelong Vitamin B7 (Biotin) can prevent or improve many of the serious problems caused by this inherited condition, especially when treatment starts early.
3. Supports normal energy metabolism: Vitamin B7 (Biotin) helps enzymes break down fats, carbohydrates and protein from food. Taking extra biotin does not raise energy levels in people who already have enough.
4. Helps hair, skin and nails when levels are low: In people who are deficient, Vitamin B7 (Biotin) can help with hair loss, skin rash and brittle nails caused by the deficiency.
5. Available on its own or in B-complex products: Check all labels so you do not take more Vitamin B7 (Biotin) than you need.

Vitamin B7 (Biotin) is generally well tolerated when taken by mouth in suitable amounts. Side effects are uncommon at usual doses, and reports of harm are rare even at high intakes.

Common Side Effects (Usually Mild)

• Mild stomach upset, such as nausea or discomfort, has occasionally been reported. Taking the dose with food may help.

Serious Side Effects (Seek Urgent Medical Attention)

• Misleading blood test results: High doses of Vitamin B7 (Biotin) can interfere with some lab tests and make results falsely high or falsely low. For example, a troponin heart test may look normal while a heart attack is actually happening. Thyroid test results may also look abnormal when your thyroid is fine. This can lead to a missed diagnosis or the wrong treatment. Always tell your doctor and the lab that you take Vitamin B7 (Biotin).
• Allergic reaction (rare): Get help straight away if you have a rash with swelling, itching, swelling of the face, lips, tongue or throat, or trouble breathing.

• Take Vitamin B7 (Biotin) exactly as your doctor advises or as written on the label. Do not take more than recommended.
• Swallow the tablet or capsule whole with a glass of plain water. Do not crush, chew or break it unless the pack says it is chewable or your doctor tells you to.
• You can take it with or without food. Take it the same way every day, either always with a meal or always on an empty stomach.
• Take it at about the same time each day so it becomes part of your routine.
• If Vitamin B7 (Biotin) is part of a multivitamin or B-complex product, follow the directions for that product. Read the labels to make sure you are not getting Vitamin B7 (Biotin) from several products at once.
• If your doctor has prescribed Vitamin B7 (Biotin) for a medical condition such as biotinidase deficiency, keep taking it for as long as advised. Do not stop on your own.
• Before any blood test, tell the doctor and laboratory staff that you take Vitamin B7 (Biotin). Ask them whether you should pause it before the test. Do not decide this on your own.

Vitamin B7 (Biotin) works as a coenzyme. This is a helper molecule that certain enzymes need before they can work. Enzymes are proteins that speed up chemical reactions inside your cells.

In the body, Vitamin B7 (Biotin) attaches to a group of enzymes called carboxylases. Their job is to add a small carbon-containing piece, called a carboxyl group, to other molecules. This is an important step in several processes:

• Acetyl-CoA carboxylase helps the body build fatty acids, the building blocks of fats.
• Pyruvate carboxylase helps the body make new glucose (sugar) when needed, for example between meals.
• Propionyl-CoA carboxylase and methylcrotonyl-CoA carboxylase help break down certain amino acids and fats so they can be used for energy.

When these enzymes are later broken down, an enzyme called biotinidase frees Vitamin B7 (Biotin) so it can be used again. People with biotinidase deficiency cannot recycle the vitamin well, so they need extra Vitamin B7 (Biotin) from supplements. Vitamin B7 (Biotin) also seems to help control which genes are switched on in cells. The body removes most of what it does not use in the urine.

• Swallow Vitamin B7 (Biotin) with plain water at about the same time each day.
• Tell every doctor and lab that you take Vitamin B7 (Biotin), especially before heart or thyroid tests.
• Check all your supplement labels, because hair, skin and nail products and multivitamins often contain Vitamin B7 (Biotin).
• Eat cooked eggs, not raw egg whites, if you are trying to keep your Vitamin B7 (Biotin) levels up.
• If you take seizure medicines, ask your doctor whether you need extra Vitamin B7 (Biotin).
• Do not expect hair or nail changes if your levels are already normal.

• Store below 30°C (86°F), or as printed on the pack, in a cool, dry place.
• Keep it away from direct sunlight, heat and moisture. Avoid storing it in the bathroom.
• Keep it in the original container with the lid tightly closed.
• Keep it out of the reach and sight of children and pets.
• Do not use it after the expiry date. Ask your pharmacist how to dispose of unused tablets safely.

• Raw egg whites: These contain avidin, a protein that binds tightly to Vitamin B7 (Biotin) and stops it from being absorbed. Eating raw egg whites regularly over a long time can lead to deficiency. Cooked eggs do not cause this problem, because heat breaks down avidin.
• Alcohol: Long-term heavy drinking reduces how well the gut absorbs Vitamin B7 (Biotin).
• Foods rich in Vitamin B7 (Biotin): Beef liver, eggs, salmon, pork, sunflower seeds, almonds and sweet potatoes contain Vitamin B7 (Biotin). You do not need to avoid them while taking a supplement.

• Seizure medicines (carbamazepine, phenytoin, phenobarbital, primidone): Taking these for a long time can lower Vitamin B7 (Biotin) levels in the body. Your doctor may check whether you need a supplement.
• Other supplements containing Vitamin B7 (Biotin): Multivitamins and beauty supplements can add up to a higher total dose than you expect. This raises the risk of lab test interference.
• Lab tests (not a medicine, but a key interaction): High doses of Vitamin B7 (Biotin) can affect lab tests that use biotin as part of how the test works (biotin-streptavidin immunoassays). These include troponin (heart) tests, thyroid tests and some other hormone tests. Always tell your doctor and the lab.

• Suspected heart attack or chest pain: Vitamin B7 (Biotin) can make a troponin blood test look falsely normal. If you go to a hospital with chest pain, tell staff right away that you take Vitamin B7 (Biotin).
• Thyroid conditions: Vitamin B7 (Biotin) can make thyroid test results misleading. The results may look like an overactive thyroid when your thyroid is actually normal, which could lead to the wrong treatment.
• Biotinidase deficiency: People with this condition need Vitamin B7 (Biotin) for life. A specialist should manage the dose, and treatment should not be stopped.
• Alcohol dependence: People with long-term heavy alcohol use are more likely to have low Vitamin B7 (Biotin) levels.
• Kidney disease and dialysis: Dialysis may change how much Vitamin B7 (Biotin) you need. Let your kidney doctor guide how you use the supplement.

The adequate daily intake from all sources (food and supplements) is:

• Birth to 6 months - 5 mcg
• 7 to 12 months - 6 mcg
• 1 to 3 years - 8 mcg
• 4 to 8 years - 12 mcg
• 9 to 13 years - 20 mcg
• 14 to 18 years - 25 mcg
• Adults, including during pregnancy - 30 mcg
• Breastfeeding - 35 mcg

No upper safe limit has been set for Vitamin B7 (Biotin). Many supplements contain 5 mg to 10 mg (5,000 to 10,000 mcg), which is far more than the body needs each day. For biotinidase deficiency, a specialist sets the dose, which is usually 5 mg to 10 mg once daily. Some people need more.

• Vitamin B7 (Biotin) is usually taken once a day unless your doctor advises otherwise.
• Always follow the dose your doctor prescribes or the dose printed on the label. Do not raise the dose on your own, because higher doses make lab test interference more likely.

Vitamin B7 (Biotin) dissolves in water, and the body removes any extra in the urine. Serious poisoning has not been commonly reported, even at high intakes. The main risk of taking too much is that it can make blood test results falsely high or falsely low. This could lead to a missed diagnosis or the wrong treatment.

If someone has swallowed a large amount, especially a child, contact a doctor, a poison control centre or the nearest emergency department. Do the same if anyone feels unwell after taking extra doses. Take the pack with you. If you need blood tests soon afterwards, tell the medical team how much Vitamin B7 (Biotin) was taken.

• Take the missed dose as soon as you remember.
• If it is almost time for your next dose, skip the missed dose and take the next one at the usual time.
• Never take two doses at once to make up for a missed one.
• If you have biotinidase deficiency and often miss doses, ask your doctor about ways to remember, such as a phone reminder or a pill box.

• Chest pain, pressure or discomfort while you take Vitamin B7 (Biotin). Call emergency services and tell staff about the supplement.
• Signs of an allergic reaction, such as swelling of the face, lips, tongue or throat, hives or trouble breathing.
• Blood test results that do not match how you feel, or a new thyroid or heart diagnosis while you take Vitamin B7 (Biotin).
• Hair loss, a rash around the eyes, nose or mouth, or brittle nails that do not improve.
• Numbness or tingling in the hands or feet, low mood, severe tiredness or hallucinations.
• In a baby or child: seizures, floppy muscles, breathing problems, or hearing or vision problems.