Oral Medications Used in Eye Care

Oral antibiotics: treat infection or modulate inflammation

In eye care, oral antibiotics are used in two different ways. One is short, therapeutic dosing for true infection. The other is longer, sub-antimicrobial dosing to reduce chronic lid and ocular surface inflammation, especially in meibomian gland dysfunction (MGD) and ocular rosacea.

• Anti-infective use: Standard or higher-dose therapy is used for adnexal and periocular infections such as preseptal cellulitis, dacryocystitis, or significant internal hordeola. Common first-line choices include cephalexin or amoxicillin-clavulanate, with alternatives chosen based on allergy history, local resistance patterns, and systemic comorbidities. If the ocular surface is involved, topical therapy from the ophthalmic antibiotics section is often layered on.
• Anti-inflammatory use: Low-dose doxycycline or pulsed azithromycin can be used as sub-antimicrobial therapy for MGD and ocular rosacea. Here, the goal is not bacterial eradication. The goal is to reduce lipase activity and matrix metalloproteinase (MMP) mediated inflammation, improve meibum quality, and stabilize the tear film, alongside measures in the dry eye plan and eyelid hygiene.

Systemic antivirals for HSV and HZO

Oral antivirals such as acyclovir, valacyclovir, and famciclovir are central to management of herpetic eye disease. In herpes zoster ophthalmicus (HZO), early systemic therapy after rash onset reduces viral replication and can reduce ocular complications and the risk of post-herpetic neuralgia. In HSV keratitis, oral regimens provide effective tissue levels without added surface toxicity from older topical agents and can be used for acute treatment and, when indicated, long-term prophylaxis. Dosing strategies and steroid co-management are covered in the antivirals section.

Oral carbonic anhydrase inhibitors in glaucoma

Acetazolamide and other oral carbonic anhydrase inhibitors (CAIs) are typically reserved for situations where rapid or substantial intraocular pressure reduction is needed beyond what topical therapy can provide. Examples include acute angle-closure, markedly elevated IOP prior to laser or surgery, or advanced disease not controlled despite maximized topical regimens outlined in the glaucoma medications section. Because systemic CAIs can cause paresthesia, fatigue, gastrointestinal upset, metabolic acidosis, electrolyte disturbance, kidney stone risk, and sulfonamide-associated reactions, they are often used as short-term bridge therapy with attention to kidney function and comorbidities.

Systemic pain control and co-management

For significant ocular or periocular pain, such as post-operative discomfort, HZO-related neuralgia, or severe corneal injury, systemic analgesics may be used alongside topical measures discussed in the pain management section. Choice of agent depends on diagnosis, comorbidities, and whether neuropathic pain is involved, with coordination with the patient's primary care or pain team when appropriate. Documentation is clearer when it distinguishes whether a medication is being used for infection, inflammation control, IOP reduction, or analgesia.