Tuberculosis (TB) is a serious lung disease caused by Mycobacterium tuberculosis bacteria. While it primarily affects the lungs, TB can also affect other parts of the body and lead to life threatening complications.

The American Lung Association estimates that 10 million people have “active” tuberculosis worldwide, though the infection is far less common in the United States. Most cases are also curable.

Antibiotics may treat most forms of TB. But if you have TB that isn’t responding to commonly used medications, you could have a form known as drug-resistant tuberculosis.

Read on to learn more about the causes of drug-resistant TB and common risk factors, along with symptoms and treatment options.

In most cases, drug-resistant TB develops when you don’t stick to your treatment plan. Not taking a full course of treatment or taking the wrong dosage can cause drug resistance.

TB itself is an airborne infection spread through prolonged exposure to someone who has an active TB infection. TB can be transmitted through droplets when a person with a TB infection:

  • talks
  • coughs
  • sneezes

After you inhale the bacterium that causes TB, it lodges in your lung tissues. From there, TB bacteria can spread into several areas of your body, including your:

  • lymph nodes
  • skin
  • other major organs

In the United States, doctors usually treat TB with a 4-month, 6-month, or 9-month course of medications.

The 4-month course includes the medications:

  • rifapentine
  • moxifloxacin
  • isoniazid
  • pyrazinamide

The 6- or 9-month course uses a regimen called RIPE:

  • rifampin
  • isoniazid
  • pyrazinamide
  • ethambutol

If you don’t follow your treatment plan, or if your condition doesn’t improve with first-line treatments, you could have drug-resistant TB. This means that the bacteria responsible for your TB infection is resistant to the standard of treatment used to get rid of it.

While it can take months or even years to develop TB after infection, you may be at a higher risk of contracting TB and developing an infection right away if you have a weakened immune system. This includes:

Additionally, you may be at risk of getting drug-resistant TB if you:

  • live in an area where TB is prevalent
  • have been exposed to someone with drug-resistant TB
  • work in an industry or setting, such as hospitals, where you may be exposed to others with drug-resistant TB
  • have a history of TB infection
  • stop taking TB medications as prescribed

The type of drug-resistant TB you may have depends on the particular drug(s) you may be resistant to. Such medications are often considered first-line TB treatments. Also, it’s possible to have more than one type of drug-resistant tuberculosis.

Types of drug-resistant TB include:

  • Mono-resistant (MR-TB). You’re resistant to one first-line TB treatment.
  • Poly-resistant (PR-TB). You’re resistant to more than one first-line treatment, aside from isoniazid and rifampin.
  • Multidrug-resistant (MDR-TB). This is a more serious subtype where you may be resistant to more than one type of drug, particularly isoniazid and rifampin.
  • Rifampin-resistant (RR-TB). You’re resistant to rifampin.
  • Pre-extensively drug-resistant (pre-XDR-TB). You’re resistant to isoniazid, rifampin, and fluoroquinolone antibiotics or a second-line injection, such as amikacin, capreomycin, and kanamycin.
  • Extensively drug-resistant (XDR-TB). You’re resistant to isoniazid, rifampin, and a fluoroquinolone antibiotic, as well as bedaquiline, linezolid, or one of the three second-line injections. While XDR-TB is rare, it’s also the most serious type of drug-resistant TB if you have a weakened immune system.

Symptoms of TB include:

  • a worsening cough that lasts for 3 weeks or more
  • coughing up mucus or blood
  • fatigue
  • weakness
  • fever
  • night sweats
  • loss of appetite
  • unintentional weight loss

Having drug-resistant TB doesn’t cause different symptoms. Instead, the symptoms last longer and don’t get better despite traditional TB drugs. If you aren’t getting better despite potent TB medications, you should see your doctor about possible drug resistance.

In antibiotic-resistant infections, first-line medications don’t get rid of harmful bacteria. The bacteria may continue to grow and spread.

TB is traditionally diagnosed with a combination of:

  • blood tests
  • lung X-rays
  • skin tests

For doctors to determine drug resistance, they’ll need more tests. This usually involves taking a culture of bacteria and then exposing it to various drugs in a lab setting. While effective, the downside is that the process can take 2 to 3 days to complete.

It’s still possible to treat drug-resistant TB, but you may not be able to take certain first-line medications doctors usually use. Treatment will depend on the type of drug-resistant TB you have. XDR-TB is the most challenging to treat due to multiple antibiotic resistance.

Coming up with a regimen for drug-resistant TB is very complicated. It involves a combination of multiple antibiotics that depend on many complex factors. Options that your doctor may consider for treating drug-resistant TB include:

  • Using a different first-line treatment. This is common in the case of MR-TB.
  • Fluoroquinolone. This is a type of antibiotic prescribed only for more complicated infections. It has potentially serious and permanent side effects that affect the muscles, joints, and nervous system.
  • Bedaquiline-linezolid-pretomanid combination therapy. Research shows that this therapy may help after 6 months of use. Side effects may include neuropathy and vision problems.

Taking more second- or third-line treatments may cause more serious side effects.

Treating drug-resistant TB also takes longer. The World Health Organization’s 2020 guidelines suggest regimens that can last between 6 and 20 months.

The best way to prevent drug-resistant TB is by trying to keep yourself safe from contracting TB-causing bacteria. You can protect yourself by avoiding others who are sick and by keeping up with recommended vaccinations and medications prescribed by your doctor.

If you come in close contact with someone who has recently developed an active TB infection, you should see a doctor right away for testing. If you are diagnosed with TB, talk with your doctor about your treatment options and whether you have the drug-resistant subtype.

If your doctor finds that you have “latent” TB, which means it has not yet developed into a disease, they may recommend taking isoniazid. Depending on the regimen, the duration of this preventive treatment can vary from 3 to 9 months.

Also, you may help prevent drug-resistant TB by taking all of your TB medications as prescribed. Skipping doses or stopping treatment altogether may increase your risk of developing drug-resistant TB.

Whether you have traditional or drug-resistant TB, it’s also important to help reduce the spread of the bacteria to others if you can. It can take a few weeks for your medications to start working, so you may need to avoid contact with others during this time. You should also avoid going to school or work until your doctor says it’s safe to return.

Is there a vaccine for TB?

The Bacille Calmette-Guérin (BCG) vaccine is used in some countries to help prevent serious TB infections in children. However, the BCG vaccine isn’t used in the United States due to a general lack of efficacy overall.

Is drug-resistant TB spread the same way as regular TB?

Yes. Drug-resistant TB is also airborne and spreads through air droplets from a person with an active TB infection. What makes drug-resistant TB different is that the bacteria that cause the infection are resistant to medications normally used to treat it.

When did drug-resistant TB start?

While the exact timeline isn’t known, scientists first identified antibiotic resistance in the 1940s. Since then, more antibiotic-resistant infections have developed, with the Centers for Disease Control and Prevention (CDC) declaring antibiotic resistance one of the “most urgent public health problems” worldwide.

Is drug-resistant TB fatal?

Most cases of TB are curable. However, drug-resistant TB is more difficult to cure because the medications normally used to treat the infection don’t work. This type of bacterial resistance could increase the risk of death from TB, making early diagnosis critical.

Due to a reduced response to typical first-line treatments, drug-resistant TB is more difficult to cure. It’s important to take available preventive measures, such as completing your course of TB treatment to avoid developing drug-resistant TB.

Cost is another consideration. Long-term TB may result in loss of income due to an inability to go to work. The cost of treatment can range from $18,000 to $513,000.

It’s also important to keep in mind that TB is among many diseases that are becoming more resistant to traditional antibiotics. If you have a weakened immune system or other risk factors, talk with a doctor about ways you can protect yourself from potentially drug-resistant infections.