Fecal Transplant Side Effects & Risks: What You Need to Know About FMT

June 6, 2023

Fecal Microbiota Transplants (FMT) are a relatively safe procedure when performed in a clinical setting with a healthy, pre-screened donor. The symptoms of stool transplants are few and are generally mild. Known major FMT risks are typically associated with lack of proper screening and care; otherwise, major risks are easily avoidable in treatment.

If you’re interested in getting FMT for you or someone you know, we’ll break down all the risks of the procedure below, and answer your burning questions including:

  • What are the FMT side effects?
  • Major risks of stool transplants
  • Is a DIY fecal transplant safe?
  • Where to learn more about fecal transplants

If you are thinking of having an FMT, here is what to expect and watch out for after having the procedure.

What are the FMT side effects?

Side effects of FMT tend to be mild and short-lived. Experiencing any of the following symptoms are normal and to be expected after receiving a fecal transplant.

  • Changes in stool - It is common to experience changes in stool after an FMT. You may find that your stool looks and even smells different, but this is normal.
  • Diarrhea - Changes in stool are common, including diarrhea post-FMT, but if the symptom persists for more than a few days, contact your doctor.
  • Constipation - Constipation after an FMT can occur, but shouldn’t last for more than a few days. If the constipation continues past this point, you should contact your doctor.
  • Abdominal discomfort - Discomfort occurs for many after having a stool transplant, but if the discomfort turns to pain, consult your doctor.
  • Cramping - Cramping is normal in the hours and day following an FMT.
  • Bloating - Bloating following the transplant is normal and should not persist much longer than a fews hours or a day.

The above-mentioned fecal transplant side effects are common and safe, however, persistence of these symptoms beyond a few days may be dangerous or indicate other serious complications. Tell your doctor if you have persistent symptoms like the ones listed above.

Major risks of stool transplants

Complications in FMT are incredibly rare when they are performed by an experienced medical professional. With proper screening and preparation, most of the risks listed below are avoidable:

  • Intestinal perforation - In rare cases some people have experienced intestinal perforation. This can be very dangerous and life-threatening, which is why proper care and follow up is necessary.
  • Physical injury - Enema, colonoscopy, or nasoenteric tube may cause injury when inserted for treatment; scraping or cutting of interior walls is possible.
  • Transferring a parasite or pathogen - Dangerous bugs or viruses may be passed through FMT. This risk can generally be avoided with proper screening, and is heightened when performing the a DIY FMT procedure.
  • Dysbiosis (unbalanced gut microbiota) - Again, this risk is generally avoidable with proper medical screening, but if the donor is not of the utmost health and/or has an unbalanced microbiome, this might worsen dysbiosis in the recipient of the sample.
  • Transferring other characteristics - Though incredibly rare, there have been case reports of donors transferring characteristics to the recipients such as obesity.

Above are only the known risks of FMT. As of yet, there is no way of knowing the long-term risk factors associated with the treatment because studies have all been done too recently. Long-term follow up of current clinical studies will be necessary in order to assess any persistent risks there might be.

Is a DIY fecal transplant safe?

DIY fecal transplants cannot be guaranteed safe. Though many of the fecal transplant risks are rare, performing FMT in a DIY fashion is not advisable, as the risk is heightened by a lack of proper care and screening. Fecal transplants should never be performed without the consultation of a doctor.

Both stool donors and recipients involved in FMT need to be thoroughly screened to make sure they are both healthy enough to participate in the procedure; that kind of screening is simply not possible in a non-clinical setting.

Where to learn more about fecal transplants

To learn more about fecal transplants, how they are performed, and what they are effective in treating, check out some of these articles and resources.

Fecal Transplant Resources Guide: 40+ Articles, Podcasts, and Sites

Find all the resources you need to educate yourself about FMT and the microbiome. This is a great place to start if you are interested in learning more about the practice.

The Rise of the Do-It-Yourself Fecal Transplant

DIY fecal transplants are becoming more and more common, read about why and how people are taking their health into their own hands.