Dear Doctors: I was sick for months with debilitating pain, extreme weight loss, fatigue and loss of appetite. I was diagnosed with C. diff related to an abdominal surgery. I’m being treated with antibiotics, but I worry about the effects on my gut microbiome. Is a fecal transplant an option?

Dear Reader: For those who are not familiar, C. diff is short for Clostridioides difficile, a potentially life-threatening bacterium. If it takes up residence in the large intestine, C. diff can cause a range of gastrointestinal symptoms. The most common are colitis, which is widespread inflammation of the colon, and persistent diarrhea. Additional symptoms include abdominal tenderness or pain, fever, nausea, loss of appetite and unintentional weight loss. Symptoms range from mild to severe and can lead to complications such as dehydration, bloody stool, low blood pressure, rapid heart rate and infection in the tissues of the colon.

C. diff infection is often associated with the use of broad-spectrum antibiotics, which disturb the equilibrium of the microbial colonies living in the colon. This disruption allows an overgrowth of opportunistic bacteria, such as C. diff, to occur. Inflammatory bowel diseases, which weaken the integrity of the colon, and reduced immunity are also risk factors.

C. diff spreads via the spores it produces. They are very hard to eradicate completely, which is why this infection is often seen in hospitals and long-term care settings.

Treatment depends on the severity of infection. For some people, stopping the broad-spectrum antibiotics that allowed C. diff to flourish can be adequate. When a C. diff infection is persistent, specific antibiotics, which target the bacterium, are prescribed.

The newest approach to aggressive or repeated C. diff infection is the fecal transplants you are asking about. Also known as fecal microbiota transplant, or FMT, the treatment involves inoculating the colon with healthy donor stool. This kick-starts the regrowth of the diverse colonies of intestinal flora that had previously kept adverse bacterial overgrowths in check.

The history of FMT dates back at least to fourth-century China, where written records detail the successful use of a fecal slurry to treat severe diarrhea. The modern version of the treatment, in which healthy stool is rigorously tested for safety and then specially treated for medical use, began in the mid-20th century.

When it comes to the success rate of FMT, the data are still not clear. This is a new approach, and treatment protocols have not yet been standardized. Initially, recovery rates were believed to be in the range of 90%. Newer data, which take into account repeat infections, suggest the success rate of FMT treatment for C. diff may be closer to 70%.

Your concerns about the antibiotic treatment you are undergoing are understandable. However, unlike broad-spectrum antibiotics, which suppress the entire gut microbiome, the drugs used in treatment of C. diff are targeted. At this time, FMT becomes an option when two rounds of antibiotic treatment fail to cure the infection. In cases of severe C. diff infection, or with recurrent infection, it may be a first-line treatment. Check with your internist to see if you may be a candidate.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o UCLA Health Sciences Media Relations, 10960 Wilshire Blvd., Suite 1955, Los Angeles, CA, 90024. Owing to the volume of mail, personal replies cannot be provided.)

Dear Doctors: I had such a bad attack of vertigo that my boyfriend drove me to urgent care. The doctor got it to go away by having me lie down and then moving my head around. Why did I have that episode of vertigo, and why did that treatment help?

Dear Reader: Vertigo is the sudden onset of a sensation of spinning or whirling. It can feel like the environment around you is in motion, or that your own body is spinning through space. The resulting dizziness can be so intense it often causes nausea.

Most episodes of vertigo arise from problems with the delicate mechanisms of the inner ear, which aid in balance. This is known as peripheral vertigo. Less common is central vertigo, which involves the brain. This classification of vertigo can arise due to physical injury or trauma, migraine, infection, cancer or stroke. Vertigo can also be a side effect of certain medications.

From your description of the treatment you received, it appears you had an episode of what is known as positional vertigo. The full medical term is benign paroxysmal positional vertigo, or BPPV. It is the most common cause of episodes of vertigo. Although it can be extremely uncomfortable -- and often frightening -- BPPV is not life-threatening. However, it can adversely affect quality of life. The dizziness it causes can also increase the risk of falling, which is a leading cause of fractures in older adults.

To understand what happened, we need to talk about the vestibular system. This is a tiny but remarkably complex set of fluid-filled structures, receptors and neural pathways located in the innermost part of the ear. Working together, the components of the vestibular system help you sense motion and detect positional changes. The brain uses this information to calibrate the physical responses needed for movement and balance.

Among the elements of the vestibular system are miniscule calcium crystals, which help convey the sensation of motion. If these crystals become dislodged, tilting the head quickly can cause them to drift out of position. This leads to the delivery of faulty data to the brain, which in turn causes the spinning and whirling symptoms of vertigo.

When your doctor manipulated the position of your head, she was using the Epley maneuver. It is named for the physician who pioneered it. The treatment involves a precise rotation of the head, with the goal of redistributing the dislodged crystals. First, the person’s head is placed in a position that triggers vertigo. They will then lie down and, with the nape of the neck at the edge of the exam table, make a slow 180-degree turn of the head.

The next step is to reposition the body so that it aligns with the head. The person will then be asked to return to an upright position. Although not physically risky, the maneuver can briefly intensify the symptoms of vertigo, and it can cause nausea or even vomiting. In most cases, the Epley maneuver resolves positional vertigo. If not, one or more repeats of the procedure may be needed.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o UCLA Health Sciences Media Relations, 10960 Wilshire Blvd., Suite 1955, Los Angeles, CA, 90024. Owing to the volume of mail, personal replies cannot be provided.)

Dear Doctors: I have dandruff, and my doctor says it’s from seborrheic dermatitis. Can you explain what that is? I’ve been using the special shampoo I was given, and it helps. When I stop using it, though, the dandruff comes right back. Also, it’s making my hair really dry.

Dear Reader: Dandruff is a condition in which the skin on the scalp begins to flake and shed. It is often caused by a mild form of an inflammatory skin condition known as seborrheic dermatitis.

The word “seborrheic” refers to the sebaceous glands. These are miniscule glands embedded in the skin, almost always alongside a hair follicle. These glands secrete a waxy and oily substance known as sebum. The degree to which someone’s hair is naturally oily or dry is connected to the activity of their sebaceous glands.

When seborrheic dermatitis develops on the scalp, it is referred to as dandruff. It is not a danger to health, and it is not contagious. The most visible symptom of dandruff is the presence of the white flakes that you have described. These are dead skin cells, which become pale and translucent as they are shed. Additional symptoms can include itching on the scalp and areas of thickened, scaly or crusty skin.

Seborrheic dermatitis is often associated with an overgrowth of a genus of fungus known as Malassezia. It is a yeast that naturally occurs on the skin. This type of yeast requires fat for nourishment, which is why it is commonly found near the sebaceous glands. When something causes an overgrowth of the yeast, it can trigger an inflammatory response. Dry or cold weather can lead to flares of dandruff symptoms. So can hormonal shifts, a buildup of hairstyling products or the warm and humid microclimate created by wearing a hat or wig.

Treatment of seborrheic dermatitis on the scalp has two main targets. One is to reduce the colonization of the Malassezia yeast. The other is to manage any symptoms of inflammation that are making the person uncomfortable. When the sebaceous glands of the scalp are overactive, they produce an abundance of sebum. This, in turn, can encourage the growth of the Malassezia yeast associated with dandruff symptoms. When this occurs, modulating sebum production is also an important part of managing the condition.

The shampoo that you have been advised to use contains an antifungal agent that is designed to slow or stop the growth of the yeast. However, because it does not completely eradicate the yeast, ongoing use of the shampoo is necessary to manage the fungal infection. Because reducing sebum production is also one of the goals of treatment, these products can lead to dry hair, as you have experienced. Dandruff shampoos also contain ingredients to ease itchiness and reduce flaking. These shampoos come in a variety of formulas, with different added ingredients. With a bit of trial and error, you can find the brand of shampoo that works best for your specific situation. Some people find using a rotation of different products can be helpful.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o UCLA Health Sciences Media Relations, 10960 Wilshire Blvd., Suite 1955, Los Angeles, CA, 90024. Owing to the volume of mail, personal replies cannot be provided.)