Ampicillin for Sinusitis: Quick Guide, Dosage & Safety

If you’ve got a sinus infection that’s not getting better, your doctor might suggest ampicillin. It’s an older‑school antibiotic that fights the bacteria behind many sinus headaches, facial pressure, and thick green mucus. Before you grab a pill, let’s break down what ampicillin does, when it’s a good fit, and what you need to watch out for.

How Ampicillin Works for Sinus Infections

Ampicillin belongs to the penicillin family. It attacks the wall of bacterial cells, causing them to burst and die. This works well for common sinus‑causing bugs like Streptococcus pneumoniae and Haemophilus influenzae. If your sinusitis is caused by a virus, ampicillin won’t help, so doctors usually confirm a bacterial cause before prescribing.

Dosage, Safety, and When to Use It

The standard adult dose is 250‑500 mg taken every 6 hours for 7‑10 days. Kids get a weight‑based dose, usually 25‑45 mg per kilogram daily, split into three or four doses. Take the medicine with a full glass of water and finish the whole course, even if you feel better early.

Common side effects include mild stomach upset, diarrhea, or a rash. If you notice severe itching, swelling, or trouble breathing, stop the med right away and call your doctor—those could be signs of an allergic reaction.

Don’t use ampicillin if you’re allergic to penicillin or have had a severe reaction before. Also, let your doctor know if you have kidney disease, as the dose may need adjustment.

Mixing ampicillin with certain foods or antacids isn’t a big issue, but avoid taking it with a lot of dairy at the exact same time, because calcium can slightly lower how much gets absorbed.

When does ampicillin make sense? If you have acute bacterial sinusitis with fever, facial pain, and symptoms lasting more than 10 days, or if symptoms get worse after a few days of feeling okay, a doctor may prescribe ampicillin. For chronic sinus issues or repeated infections, a different antibiotic might be chosen based on culture results.

Always ask your pharmacist if you’re on other meds, especially blood thinners or oral contraceptives, because antibiotics can sometimes change how those work. Most of the time, ampicillin doesn’t cause big interactions, but it’s worth checking.

Remember, antibiotics aren’t a cure‑all. Keeping your nasal passages clear with saline rinses, staying hydrated, and using a humidifier can help the medicine work faster and keep symptoms down.

Bottom line: ampicillin can be an effective short‑term weapon against bacterial sinusitis when used correctly. Follow the prescribed dose, finish the course, and watch for side effects. If you’re unsure whether it’s right for you, ask your doctor for a quick explanation of why they chose it over other options.