Tepezza (teprotumumab) is a significant advancement in the treatment of Thyroid Eye Disease (TED), offering hope to many patients suffering from this condition [1.4.2]. However, like most medications, it is associated with a range of potential side effects. Among the most frequently reported are gastrointestinal (GI) issues, with diarrhea being a notable concern for many patients [1.2.1, 1.5.3].
What is Tepezza and How Does It Work?
Tepezza is an FDA-approved prescription medicine administered via intravenous (IV) infusion for the treatment of Thyroid Eye Disease [1.4.2]. TED is a rare autoimmune condition where the body's immune system attacks the tissues behind the eyes, causing inflammation, eye bulging (proptosis), double vision, and pain [1.4.2].
The medication works by targeting and blocking the insulin-like growth factor-1 receptor (IGF-1R) [1.4.1]. This receptor is overexpressed on orbital fibroblasts in TED patients and plays a key role in the inflammation and tissue expansion characteristic of the disease [1.4.1, 1.4.3]. By inhibiting IGF-1R, Tepezza helps to reduce the underlying cause of the orbital tissue remodeling [1.4.1].
The Connection: Can Tepezza Cause Diarrhea?
Yes, Tepezza can cause diarrhea [1.2.2]. Clinical studies have consistently listed diarrhea as one of the most common adverse reactions to the treatment. The reported incidence varies across different studies, with figures cited between 12% and 27.4% [1.2.1, 1.2.2, 1.6.8]. In most cases, the diarrhea experienced is mild to moderate [1.6.7].
The likely mechanism behind this side effect is related to Tepezza's mode of action. The insulin-like growth factor-1 receptor (IGF-1R), which Tepezza blocks, is not only found in eye tissues but is also expressed on intestinal epithelium and smooth muscle cells [1.4.5, 1.6.2]. IGF-1 is believed to contribute to mucosal proliferation, repair, and the reduction of intestinal inflammation [1.4.5]. By inhibiting this receptor systemically, Tepezza may disrupt the normal function and balance of the gastrointestinal tract, leading to symptoms like diarrhea [1.4.5].
Special Consideration: Inflammatory Bowel Disease (IBD)
It is crucial for patients with a history of Inflammatory Bowel Disease (IBD), such as Crohn's disease or ulcerative colitis, to discuss their condition with their doctor before starting Tepezza. The medication carries a warning that it may cause an exacerbation or flare-up of preexisting IBD [1.3.2, 1.6.1]. Symptoms of a flare-up can include an increased number of loose stools, stomach pain, cramps, and blood in the stool [1.3.3, 1.5.1]. In clinical trials, some patients with a history of IBD had to discontinue treatment due to severe diarrhea [1.5.8, 1.6.2].
Comparison of Common Tepezza Side Effects
Diarrhea is just one of several potential side effects of Tepezza. To provide context, the table below compares the frequency of common adverse reactions as reported in clinical studies [1.2.1, 1.2.2, 1.6.7].
| Side Effect Category | Specific Side Effect | Reported Frequency (%) |
|---|---|---|
| Gastrointestinal | Nausea | 17% [1.2.1] |
| Diarrhea | 12-27% [1.2.1, 1.6.8] | |
| Taste Changes | 8% [1.2.1] | |
| Musculoskeletal | Muscle Spasms/Cramps | 25% [1.2.1] |
| Dermatological | Hair Loss (Alopecia) | 13% [1.2.1] |
| Dry Skin | 8% [1.2.1] | |
| General | Fatigue | 12% [1.2.1] |
| Metabolic | High Blood Sugar (Hyperglycemia) | 10% [1.2.1] |
| Neurological | Headache | 8% [1.2.1] |
| Otic | Hearing Problems | 10% [1.2.1] |
Managing Diarrhea During Tepezza Treatment
For patients who experience diarrhea while on Tepezza, several management strategies can help. It's essential to communicate with your healthcare provider about any side effects you experience [1.2.1].
- Stay Hydrated: Drink plenty of fluids like water or broth to prevent dehydration.
- Dietary Adjustments: Avoid foods that can worsen diarrhea, such as spicy, greasy, or high-fiber foods [1.3.4]. The BRAT diet (bananas, rice, applesauce, toast) may be helpful for some.
- Consult Your Doctor: Always talk to your doctor before taking any over-the-counter anti-diarrhea medications to ensure they are safe to use with your treatment.
- Monitor Symptoms: Keep track of the frequency and severity of your symptoms. If diarrhea is severe, persistent, or accompanied by blood, severe abdominal pain, or fever, contact your doctor immediately as it could indicate a more serious issue like an IBD flare-up [1.3.1, 1.5.7].
Conclusion
Diarrhea is a well-documented and relatively common side effect for patients undergoing treatment with Tepezza for Thyroid Eye Disease, stemming from the drug's mechanism of inhibiting the IGF-1R in the gastrointestinal tract [1.4.5, 1.6.2]. While it is typically mild and manageable for most, it is a significant consideration, especially for individuals with a history of IBD [1.6.1]. Open and continuous communication with a healthcare provider is key to safely managing any side effects, ensuring that the therapeutic benefits of Tepezza can be achieved with minimal disruption and discomfort. For more information, you can consult the official Tepezza website.
