From the Guidelines
Isoniazid does not commonly cause direct vision-related side effects, but it can lead to peripheral neuropathy related to pyridoxine deficiency, which may indirectly affect vision if left untreated. According to the evidence provided in the study published in the American Journal of Respiratory and Critical Care Medicine 1, the major side effects of Isoniazid include hypersensitivity, hepatitis, and peripheral neuropathy related to pyridoxine deficiency. However, vision-related side effects such as optic neuritis are more commonly associated with Ethambutol, another drug used in the treatment of mycobacterial diseases, as stated in the same study 1.
Key Points to Consider:
- Isoniazid's side effect profile does not typically include direct vision-related issues like optic neuritis, which is a concern with Ethambutol therapy 1.
- Peripheral neuropathy, a known side effect of Isoniazid, can be prevented or managed with pyridoxine supplementation, reducing the risk of indirect vision problems due to neurological deficits 1.
- Monitoring for Isoniazid toxicity involves clinical symptoms and periodic liver function tests (ALT or AST determinations), especially in the first three months of therapy, but does not typically include routine vision tests unless there are symptoms suggesting neuropathy or other neurological issues 1.
- The evidence suggests that while Isoniazid has several potential side effects, direct vision-related problems are not commonly among them, unlike with some other drugs used for similar indications 1.
Clinical Implications:
- Patients on Isoniazid should be monitored for signs of peripheral neuropathy and advised on the importance of pyridoxine supplementation to prevent this condition.
- Any changes in vision should be promptly reported to healthcare providers, although this is more relevant for patients on Ethambutol.
- The focus of monitoring Isoniazid therapy should remain on liver function and clinical symptoms of hypersensitivity or neuropathy, with an understanding that vision problems are less likely but can be indirectly related to the drug's side effect profile.
From the FDA Drug Label
Nausea, vomiting, dizziness, slurring of speech, blurring of vision, and visual hallucinations (including bright colors and strange designs) are among the early manifestations With marked overdosage, respiratory distress and CNS depression, progressing rapidly from stupor to profound coma, are to be expected, along with severe, intractable seizures.
The vision-related side effects of Isoniazid (Isonicotinic Hydrazide) include:
- Blurring of vision
- Visual hallucinations, which may include seeing:
- Bright colors
- Strange designs These effects are associated with isoniazid overdosage 2.
From the Research
Vision-Related Side Effects of Isoniazid
The vision-related side effects of Isoniazid (Isonicotinic Hydrazide) include:
- Optic neuropathy, which can lead to decreased visual acuity, deficits in color vision, and cecocentral scotomas 3, 4, 5, 6
- Bilateral toxic optic neuropathy, which can be reversible with prompt recognition and treatment 5
- Severe and reversible optic neuropathy, which can manifest as a decrease in visual acuity, deficits in color vision, and cecocentral scotomas 6
- Optic neuritis, which can be associated with concurrent etanercept and isoniazid therapy 4
Risk Factors and Prevention
The risk of vision-related side effects from Isoniazid can be increased by:
- High dosages of the drug, particularly in malnourished patients 7
- Concurrent use of other medications, such as etanercept 4
- Use of Isoniazid in combination with other antimicrobial agents, such as ethambutol 6
Monitoring and Treatment
Regular ophthalmologic examinations are important for monitoring patients on Isoniazid therapy, particularly those at high risk of vision-related side effects 3, 6 Prompt recognition and treatment of adverse drug reactions can reduce associated morbidity 5 Discontinuation of Isoniazid and other offending medications may be necessary to prevent further vision loss 4, 6