From the Guidelines

The best outpatient antibiotic regimen for phlebitis is clindamycin or trimethoprim-sulfamethoxazole (TMP-SMX).

Phlebitis is often associated with septic phlebitis, which requires antibiotic therapy, as stated in 1 and 1.
For outpatients with purulent cellulitis, empirical therapy for CA-MRSA is recommended, and options include clindamycin, TMP-SMX, a tetracycline (doxycycline or minocycline), and linezolid, as mentioned in 1 and 1.
The Infectious Diseases Society of America guidelines recommend clindamycin, TMP-SMX, doxycycline, and linezolid as options for empirical coverage of CA-MRSA in outpatients with SSTI, as stated in 1 and 1.
A more recent study 1 suggests that clindamycin and TMP-SMX are suitable options for the treatment of skin and soft tissue infections, including phlebitis.

Clindamycin: 300-450 mg orally every 6-8 hours for 5-10 days, as recommended in 1 and 1.
TMP-SMX: 160/800 mg orally every 12 hours for 5-10 days, as recommended in 1 and 1.

The choice of antibiotic should be individualized based on the patient's clinical response and susceptibility patterns, as stated in 1 and 1.
Vancomycin and linezolid are alternative options for patients who are allergic to clindamycin or TMP-SMX, or in cases where MRSA is suspected, as mentioned in 1 and 1.

From the Research

The following antibiotic regimens have been studied in the context of phlebitis treatment:

Dalbavancin has been used to treat methicillin-sensitive Staphylococcus aureus (MSSA) bacteremia secondary to septic phlebitis, with a treatment duration of 14 days 2.
Cephapirin and cephalothin have been compared in terms of their tendency to cause phlebitis, with cephapirin causing less phlebitis than cephalothin 3.
Vancomycin infusion methods have been studied to prevent phlebitis in children, with a significant reduction in phlebitis incidence using a phlebitis prevention guideline 4.

Certain antibiotics have been associated with a higher risk of phlebitis, including:

Dicloxacillin and erythromycin, which had the greatest tendency to cause phlebitis in a prospective observational study 5.
Benzylpenicillin, cefuroxime, and cloxacillin, which were also associated with a greater risk of phlebitis 5.
Cephalothin, which had a high frequency of phlebitis when first introduced, but has since been reformulated to reduce this risk 3.

When treating phlebitis, it is essential to consider the following:

The material causing the thrombophlebitis should be withdrawn immediately 6.
A specific antibiotic treatment should be instituted 24 to 36 hours later 6.
Surgical ligation may be necessary in some cases, depending on the localization of the phlebitis 6.