What Is Dicloxacillin? Uses, Dosage, and What You Need to Know in 2026

If your doctor prescribed Dicloxacillin, you may be wondering what it is, how it works, and what to expect. This guide covers everything patients need to know — from what Dicloxacillin treats to exactly how to take it.

What Is Dicloxacillin?

Dicloxacillin is a prescription antibiotic in the penicillin family. Specifically, it belongs to a subgroup called penicillinase-resistant penicillins, which means it's designed to fight bacteria that have developed resistance to ordinary penicillin by producing a defensive enzyme called penicillinase (also known as beta-lactamase).

The generic name is dicloxacillin sodium. The former brand name was Dynapen, which has been discontinued. All Dicloxacillin available today is generic. It was first patented in 1961 and approved by the FDA for medical use in 1968, making it a well-established medication with decades of clinical experience.

What Infections Does Dicloxacillin Treat?

Dicloxacillin is specifically indicated for infections caused by penicillinase-producing staphylococci — most commonly methicillin-susceptible Staphylococcus aureus (MSSA). These are the types of staph bacteria that are "regular" staph, not drug-resistant MRSA.

Common conditions Dicloxacillin is prescribed for include:

Cellulitis — Bacterial skin infection causing redness, warmth, and swelling

Impetigo — Highly contagious skin infection common in children

Folliculitis, boils, and carbuncles — Infections of hair follicles or skin glands

Mastitis — Breast tissue infection, often in breastfeeding mothers

Bone infections (osteomyelitis) — Serious infections of the bone caused by susceptible staphylococci

Important: Dicloxacillin does NOT work for MRSA (methicillin-resistant Staphylococcus aureus), viruses (like colds or flu), or most other types of bacteria. It's a targeted, narrow-spectrum antibiotic.

What Forms Does Dicloxacillin Come In?

Dicloxacillin is available as oral capsules in two strengths:

250 mg capsules — Often used for children or milder infections

500 mg capsules — The most common adult dose for skin infections

A powder for oral suspension is also commercially available for patients who cannot swallow capsules.

Dicloxacillin Dosage: What's Typical?

Always follow your doctor's specific instructions. General dosage guidelines include:

Adults: 250-500 mg every 6 hours (four times daily) for mild-to-moderate infections. Up to 1 g every 6 hours for more severe infections.

Children: 12.5-25 mg per kg of body weight per day, divided into doses every 6 hours. Your child's doctor will calculate the right dose.

Duration: Usually 7-14 days for skin infections, but duration varies by infection type and severity.

How to Take Dicloxacillin Correctly

Taking Dicloxacillin correctly is important for it to work and to avoid side effects:

Take on an empty stomach: At least 1 hour before or 2 hours after a meal. Food significantly reduces absorption.

Take with plenty of water: At least 4 ounces (120 mL) per dose.

Stay upright: Sit or stand for at least 30 minutes after taking each dose. Do not lie down immediately.

Space doses evenly: Every 6 hours means roughly 6 AM, 12 PM, 6 PM, and midnight — set reminders on your phone.

Finish the full course: Even if you feel better after a few days, complete all your doses to prevent antibiotic resistance.

Is Dicloxacillin a Controlled Substance?

No. Dicloxacillin is not a controlled substance and is not scheduled by the DEA. It's a standard prescription antibiotic that any licensed prescriber can order. There are no special refill restrictions related to controlled substance laws.

What If I Can't Find Dicloxacillin at My Pharmacy?

Dicloxacillin is a niche generic antibiotic that's not stocked in large quantities at every pharmacy. If your local pharmacy doesn't have it, medfinder can search nearby pharmacies on your behalf and text you the results. If it's truly unavailable in your area, see our guide to alternatives to Dicloxacillin for options to discuss with your doctor.