Doxycycline 100 mg: What You Need to Know

Doxycycline is an antibiotic that doctors often prescribe for infections like acne, respiratory illnesses, and Lyme disease. The 100 mg tablet is the most common strength you’ll see on a prescription label. Knowing how to take it, what it does, and what to watch out for can make your treatment smoother and safer.

How to Take Doxycycline Correctly

First, follow the dosage your doctor gave you. Usually, adults take one 100 mg tablet once or twice a day with a full glass of water. Taking it with food can help avoid stomach upset, but avoid dairy products or calcium‑rich drinks right before or after the dose because they can lower the drug’s absorption.

Stay upright for at least 30 minutes after swallowing the tablet. This simple step helps prevent irritation or ulcers in the esophagus. If you miss a dose, take it as soon as you remember—unless it’s almost time for your next dose. In that case, skip the missed one and continue with your regular schedule. Don’t double‑up.

Finish the entire course, even if you feel better early on. Stopping early can let the infection come back stronger and may cause antibiotic resistance. If you’re on a long‑term regimen for acne, your doctor might schedule regular check‑ins to see how you’re responding.

Possible Side Effects & When to Call a Doctor

Doxycycline is generally well‑tolerated, but you might notice some common side effects. Upset stomach, nausea, or mild diarrhea are typical, especially in the first few days. Taking the drug with food or a probiotic can ease these symptoms.

Sun sensitivity is another thing to watch. Doxycycline can make your skin more prone to burns, so use sunscreen, wear hats, and avoid prolonged sun exposure while you’re on the medication.

Rarely, you could develop a severe allergic reaction—rash, itching, swelling, or breathing trouble. If any of these appear, get medical help right away. Also, look out for signs of a yeast infection, especially if you’re on a long course.

Women who are pregnant, planning to become pregnant, or breastfeeding should discuss doxycycline with their doctor, as it’s not the first choice for these situations. Kids under 8 years old usually avoid doxycycline because of teeth staining, unless the doctor decides the benefits outweigh the risks.

If you notice persistent vomiting, dark urine, or severe abdominal pain, call your doctor. These could be signs of a more serious problem that needs attention.

Finally, keep all your follow‑up appointments. Your doctor may order blood tests to check liver function or monitor any other issues, especially if you’re on doxycycline for a long time.

Bottom line: take the pill exactly as prescribed, stay hydrated, protect your skin from the sun, and watch for any unusual symptoms. Doing these simple things helps you get the most out of doxycycline 100 mg while staying safe.