Do not start an empirical broad-spectrum antibiotic on your own. With a cold followed by a few days of evening fever, viral illnesses are more common than bacterial infections, and antibiotics will not treat them. They can cause diarrhea, allergy, drug interactions, and antibiotic resistance, while also making the real cause harder to identify.

There is no “perfect” antibiotic without an examination and, if needed, tests. In adults, antibiotics for sinus infection are usually considered only when symptoms are severe with fever at least 39°C for 3 to 4 days, persist beyond 10 days without improvement, or worsen after initially improving, per CDC outpatient guidance.

Get urgent medical care now if you have shortness of breath, chest pain, confusion, severe headache or neck stiffness, fainting, persistent vomiting, dehydration or very low urine output, rash or bleeding/bruising, severe abdominal pain, oxygen saturation below 94% if available, fever 39°C or above that is persistent, or if you are pregnant, immunocompromised, elderly, or have major heart/lung/kidney disease.

Do not use ibuprofen, aspirin, or another NSAID until dengue is reasonably excluded if you are in an area where dengue is common and have significant fever/body aches or rash, unless a clinician tells you it is appropriate.

I can’t safely recommend any broad-spectrum antibiotic for this situation. Fever after a cold can be viral, COVID-19/influenza, or a locally common infection such as dengue or malaria. The right treatment differs completely, and taking antibiotics such as azithromycin, amoxicillin-clavulanate, cefixime, levofloxacin, or ciprofloxacin blindly can cause harm and may delay the correct diagnosis.

For ordinary colds, uncomplicated bronchitis, and most viral upper respiratory infections, antibiotics do not help. A recent Cochrane review found no meaningful benefit for antibiotics in the common cold, with increased adverse effects: Cochrane review on cold antibiotics. The CDC adult guidance advises assessing for bacterial sinusitis only if symptoms are severe, persist more than 10 days without improvement, or worsen after initial improvement.

Because you have had fever for several days, arrange an in-person medical assessment today or within 24 hours. They can check temperature, oxygen level, lungs, throat, urine, and decide whether tests for COVID/flu, CBC, malaria, dengue, or a chest X-ray are appropriate for your area and symptoms.

Until then: fluids, rest, and paracetamol/acetaminophen for fever if safe for you. Avoid ibuprofen/aspirin if dengue is possible unless a clinician advises it.

Seek urgent care now for breathing difficulty, chest pain, persistent high fever, severe weakness, confusion, rash/bleeding, severe headache, repeated vomiting, low urine output, or oxygen saturation below 94%.