Individuals with illnesses caused by bacterial infection may be prescribed to take antibiotics. However, such medications may cause a temporary reaction in some people, like fevers, chills, vomiting, or headache.

In these cases, they may be experiencing the Herx effect.

This article discusses the Herx effect, how people get affected, and how long the effects last. The potential of cannabidiol or CBD to cause the Herx effect is also covered.

CBD Oil and the Herx Effect

The Herx effect is a temporary clinical phenomenon characterized by fever, headache, chills, or vomiting among some individuals taking antibiotics.

CBD oil is a cannabis extract containing CBD that researchers say may have antimicrobial and antibacterial properties(1).

These properties may be comparable to the effects of antibiotics. However, studies have yet to determine if CBD also causes the Herx effect.

Side Effects of CBD Oil

Despite its purported health benefits, CBD may produce adverse effects. Some documented side effects include dry mouth, fatigue, appetite loss, drowsiness, and diarrhea(2).

CBD may also interfere with other medicines or cause blood thinning(3). In this case, a grapefruit warning may be placed on the product label.

Products with a grapefruit warning may prevent other medications from metabolizing in the body. This effect may cause most drugs to remain in the blood, leading to an overdose.

Knowing that antibiotic treatment may cause a Herx effect, there is a possibility that taking CBD, if conclusively proven to have antibiotic properties, may cause such a reaction.

A 2020 study mentioned that CBD may have potential antimicrobial and antibacterial properties(4). However, the study is not conclusive whether CBD may be treated as an antibiotic.

To date, scientific data on CBD’s antibiotic properties are insufficient. Additional studies are needed to conclude if CBD may cause the Herx effect.

What Is the Herx Effect?

The Jarisch-Herxheimer reaction, sometimes called the Herx effect or JHR, is a short-term clinical phenomenon affecting individuals undergoing antibiotic treatment for spirochete infection.

Spirochetes are spiral-shaped bacteria associated with specific diseases, like Lyme disease, syphilis, and relapsing fever.

JHR may be associated with the use of antibiotics such as penicillin, tetracycline, and erythromycin. Newer antibiotics like azithromycin, ciprofloxacin, clarithromycin, meropenem may also cause JHR(5).

Individuals affected by JHR may experience symptoms like fever, chills, vomiting, headache, hyperventilation, and exacerbation of skin lesions.

JHR was first described in the 1800s by an Austrian dermatologist named Adolf Jarisch. The reaction was first observed in a syphilis patient whose skin lesions worsened after receiving mercurial compound treatment.

A similar reaction was observed in the 1900s by a German dermatologist named Karl Herxheimer.

JHR symptoms usually start two hours from antibiotic administration and resolve within 24 hours(6).

Despite CBD’s purported antimicrobial and antibacterial properties(7), more studies are needed to confirm its potential to produce the Herx effect.

More on CBD

What Is CBD Oil?

CBD oil contains cannabidiol or CBD, a chemical compound purported to have anti-anxiety, anti-seizure, anti-pain, and anti-inflammatory properties(8).

CBD is a phytocannabinoid that interacts with the body’s endocannabinoid system (ECS). The ECS maintains the body’s balance or homeostasis and keeps the body healthy.

CBD is a primary component of the FDA-approved Epidiolex, the first cannabis-based medicine to treat seizures associated with epilepsy(9).

One study mentioned that CBD may have antimicrobial and antibacterial properties(10). However, more studies are still needed to conclusively confirm CBD’s effectiveness in reducing or preventing bacterial growth.

Does CBD Oil Work?

Aside from Epidiolex, the FDA has not yet approved CBD oil as a prescription drug for the medical treatment of diseases(11).

Several studies stated that CBD has anti-inflammatory, anti-anxiety, anti-seizure, and anti-pain effects(12).

A 2015 study mentioned that CBD may help with multiple anxiety disorders(13).

These disorders include social anxiety disorder (SAD), generalized anxiety disorder (GAD), obsessive-compulsive disorder (OCD), and post-traumatic stress disorder (PTSD).

Another study showed CBD to have potential antioxidant and anti-inflammatory effects(14).

However, the study also mentioned that CBD may interfere with the cytochrome P450 3A and P450 2C enzymes necessary for metabolizing other drugs.

5 Possible Reasons Why CBD Is Not Working

There are some reasons why CBD may not work for some people. Some of those reasons include:

  • The CBD product does not have a COA – Certificates of analysis or COAs are third-party lab results containing the actual CBD contents of the product.

COAs prove that the results and the manufacturer’s claims match. These results must be publicly available on the CBD company’s website.

  • COA results do not match the manufacturer’s claimsIn some cases, the CBD product details on the website and label are significantly different from the COA results. Thus, some CBD products may pose a potential health risk.
  • The CBD product’s claims are unsubstantiated – Statements like, “This product treats this disease” should be evaluated carefully, especially since the FDA has not approved CBD for the treatment of any illness.

The only exception to date is Epidiolex, which is FDA-approved to help with seizures caused by epilepsy(15).

  • The user has a low tolerance for side effects – If someone has severe or recurring reactions toward CBD, like diarrhea or fatigue, they may need to consider other alternatives for their condition.
  • CBD products are illegal in some places – Purchasing or using certain CBD products, such as those high in THC, may get the user in legal trouble in some states.

Under U.S. federal law, CBD derived from hemp that does not contain more than 0.3% THC is no longer on the list of controlled substances. While this makes CBD federally legal, the FDA still reserves the right to regulate cannabis products(16).

Additionally, each state has varying restriction levels regarding CBD use. Individuals should check their state’s laws to determine if purchasing and using CBD is legal or not.

Common Forms of CBD

Most CBD products are marketed as full-spectrum, broad-spectrum, or isolates.

Full-spectrum CBD products usually contain all the compounds extracted from the cannabis plant, including tetrahydrocannabinol (THC), terpenes, and flavonoids.

THC is a psychoactive cannabis substance that gives a feeling of being high. On the other hand, terpenes are plant compounds that create an aromatic effect, and flavonoids are natural substances with antioxidative properties.

Meanwhile, broad-spectrum products contain similar components as full-spectrum CBD, except for THC.

Isolates are pure CBD only and do not contain any other compound or cannabinoid.

From these three forms, CBD may be formulated into different product types, such as tinctures, capsules, edibles, vapes, and topicals.

Tinctures are usually administered sublingually or under the tongue using a dropper. Capsules and edibles are ingested orally. Vapes are administered through inhalation. Topicals like creams or lotions are commonly applied to the skin.

The Bottom Line

To date, there is still insufficient scientific information on CBD’s potential antibiotic effects. More conclusive data is needed to determine if CBD may cause JHR in individuals with spirochete infection.

Individuals experiencing symptoms indicative of bacterial infection should first consult a doctor for diagnosis and treatment recommendations.


  1. The Antimicrobial Activity of Cannabinoids https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7400265/
  2. What are the benefits of CBD — and is it safe to use? https://www.mayoclinic.org/healthy-lifestyle/consumer-health/expert-answers/is-cbd-safe-and-effective/faq-20446700 
  3. Cannabidiol (CBD)-what we know and what we don’t https://www.health.harvard.edu/blog/cannabidiol-cbd-what-we-know-and-what-we-dont-2018082414476 
  4. The Antimicrobial Activity of Cannabinoids https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7400265/
  5. Jarisch Herxheimer Reaction https://www.ncbi.nlm.nih.gov/books/NBK557820/ 
  6. Ibid.
  7. The Antimicrobial Activity of Cannabinoids https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7400265/
  8. Cannabidiol (CBD)-what we know and what we don’t https://www.health.harvard.edu/blog/cannabidiol-cbd-what-we-know-and-what-we-dont-2018082414476 
  9. FDA Approves First Drug Comprised of an Active Ingredient Derived from Marijuana to Treat Rare, Severe Forms of Epilepsy https://www.fda.gov/news-events/press-announcements/fda-approves-first-drug-comprised-active-ingredient-derived-marijuana-treat-rare-severe-forms
  10. The Antimicrobial Activity of Cannabinoids https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7400265/ 
  11. What You Need to Know (And What We’re Working to Find Out) About Products Containing Cannabis or Cannabis-derived Compounds, Including CBD https://www.fda.gov/consumers/consumer-updates/what-you-need-know-and-what-were-working-find-out-about-products-containing-cannabis-or-cannabis 
  12. Cannabidiol (CBD)-what we know and what we don’t https://www.health.harvard.edu/blog/cannabidiol-cbd-what-we-know-and-what-we-dont-2018082414476 
  13. Cannabidiol as a Potential Treatment for Anxiety Disorders https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4604171/ 
  14. Antioxidative and Anti-Inflammatory Properties of Cannabidiol https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7023045/ 
  15. FDA Approves First Drug Comprised of an Active Ingredient Derived from Marijuana to Treat Rare, Severe Forms of Epilepsy https://www.fda.gov/news-events/press-announcements/fda-approves-first-drug-comprised-active-ingredient-derived-marijuana-treat-rare-severe-forms 
  16. FDA Regulation of Cannabis and Cannabis-Derived Products, Including Cannabidiol (CBD) https://www.fda.gov/news-events/public-health-focus/fda-regulation-cannabis-and-cannabis-derived-products-including-cannabidiol-cbd
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