Post-Antibiotic Rebuild: A 2–4 Week Plan Back to Steady
Antibiotics can save the day—and scramble your gut. If you’ve noticed looser stools, bloat, or swings since a course of antibiotics, use this phased, food-first plan to get back to Bristol Types 3–4.
What antibiotics change (plain English)
They reduce bacterial diversity, including some helpful species that help firm/soften stool.
Transit can speed up (loose/urgent) or sometimes slow down (hard/pellet-y).
The fix isn’t restriction—it’s a calm rebuild: soluble-first foods, smart hydration, steady routine, and paced fiber expansion.
The 3 Phases (2–4 weeks total)
Phase 1 — Settle (Days 1–4)
Goal: Calm looseness/irritation while staying nourished.
Do:
Soluble-first meals: oats/cream of oats, white rice or congee, potatoes, canned pumpkin, applesauce, ripe banana, well-cooked carrots/zucchini/green beans.
Gentle proteins: eggs, tofu, tender chicken/white fish (small portions).
Meals & rhythm: small + frequent; walk 10–20 min after main meals.
Hydration: 1.5–2.5 L/day + ORS 1–2×/day if loose/urgent (24–48 h).
Pause just for now: >1 cup caffeine, alcohol, sugar alcohols, big raw salads, large bean portions, fried/spicy meals.
Sample day:
Breakfast: cream of oats + applesauce
Snack: banana
Lunch: white rice + poached chicken + soft carrots
Snack: yogurt/kefir (or lactose-free)
Dinner: mashed potatoes + tofu + green beans (soft)
Phase 2 — Build (Days 5–14)
Goal: Re-introduce variety and fiber without flare-ups.
Do:
Raise fiber slowly: +3–5 g every 3–4 days, keep ≥50–70% soluble.
Add back: oat bran, barley, cooked spinach/mushrooms, small lentil portions (start ¼–½ cup, well-cooked).
Yogurt/kefir (or lactose-free) if tolerated; otherwise run a lactose-light trial for 1–2 weeks.
Optional (education only): a short probiotic trial for 2–4 weeks—commonly used strains include Lactobacillus rhamnosus GG or Saccharomyces boulardii; stop if not helpful or if contraindicated. Discuss with your clinician.
Constipation-leaning?
Ensure fluids 2–3 L/day (if not restricted), keep a soluble anchor at breakfast (oats/psyllium), consider 2 kiwis/day or 2 Tbsp ground flax.
Diarrhea-leaning?
Keep total fiber 15–20 g/day at first, soluble-heavy; use ORS on very loose days.
Phase 3 — Re-expand (Days 15–28)
Goal: Return to your long-term pattern without re-triggering swings.
Do:
Add one “trimmed” item at a time: whole-grain swaps, beans/legumes (½ cup), more raw veg—one change per 48 h.
Keep portions modest; stick with post-meal walks and the BM window after breakfast.
If something triggers symptoms, remove it and retry in 2–4 weeks at a smaller portion.
Your daily rhythm (copy/paste)
On waking: warm drink (8–12 oz) + 3 slow belly breaths
Breakfast ≤60 min: include a soluble anchor (oats/psyllium/chia/pumpkin)
Post-meal walks: 10–20 minutes after breakfast, lunch, dinner
BM window: 5–10 min, footstool, lean forward, long exhale, device-free
Hydration: set a bottle goal; finish most by early evening
The Fiber Ladder (without the bloat)
Days 1–3: ~+5 g/day using soluble (oats, chia/flax, cooked carrots/pumpkin).
Days 4–6: Hold total steady; keep veg soft/cooked.
Days 7–10:
Constipation-leaning: add bran 2–3 Tbsp or a whole-grain swap; trial ½ cup lentils.
Diarrhea-leaning: hold here; stay soluble-heavy.
Days 11–14: Personalize: 25–35 g/day (constipation) or 15–25 g/day (diarrhea-leaning).
Troubleshooting (quick table)
Issue Likely Cause Quick Fix
Still Type 7 on Days 1–3 Not enough soluble/electrolytes Add banana + applesauce + pumpkin daily; ORS 1–2×/day
Gas/bloat when adding variety Fiber jump too fast / big raw veg Increase 3–5 g every 3–4 days; keep veg well-cooked; split fiber across meals
Hard pellets by Week 2 Fluids low / no soluble anchor Push fluids to 2.5–3 L/day; add psyllium 2–3 g/day; kiwifruit or flax
Loose after dairy Lactose sensitivity post-ABX Go lactose-light for 1–2 weeks; retry small portions later
Urgency after large lunch Bolus too big / caffeine timing Smaller, frequent meals; move coffee earlier; add a soluble anchor
When to ask about specific causes
Post-cholecystectomy (gallbladder removed): consider bile-acid diarrhea; ask your clinician about binders.
Persistent bloat + alternating stools: consider SIBO evaluation (breath test).
Ongoing watery stools, weight loss, anemia, nocturnal diarrhea, autoimmune history: evaluate for IBD/microscopic colitis/celiac.
Red flags (don’t DIY)
Blood in stool (red/black), persistent fever, severe abdominal pain, signs of dehydration (dizziness, very dark urine, minimal urination), unintentional weight loss, anemia, nighttime symptoms, or a new change after age 50. Seek medical care.
7-Day Rebuild Checklist
☐ Soluble-first at breakfast (daily)
☐ 10–20 min walk after each main meal
☐ BM window (footstool, relaxed exhale) after breakfast
☐ Hydration target met (write a number)
☐ One change at a time; track for 48 h
☐ Log Bristol, urgency, pain/bloat, fiber, fluids, triggers (use the diary)
Get Free Tool To Steady Your Gut":
Make your rebuild simple with the exact printables I use with clients:
1:1 GI-MAP® Testing & Nutrition Consult
If symptoms persist beyond the rebuild—or you want clarity on what changed—data can help.
Includes:
GI-MAP® kit + step-by-step collection instructions
Dietitian interpretation (pathogens, inflammation, digestion markers)
A phased, food-first plan with targeted supplements if appropriate
Follow-ups to translate results into Types 3–4 most days
→ [Learn More About a GI-MAP® consult]
Balanced Belly Beverages Recipe Book
Hydration makes this rebuild work. Get 60+ gentle beverage recipes (ORS variations, ginger-mint coolers, oat blends, light smoothies) plus timing cues to support the gastrocolic reflex.
→ [Get the Balanced Belly Beverages Book]
Ready for steady, comfortable bowel movements?
Grab Steady Stools: A Practical Guide to Keeping Bowel Movements Consistent on Amazon and follow the step-by-step plans (Constipation, Diarrhea, or Mixed) plus printables to track what’s working.
👉 Click here to get the ebook on Amazon
Author: Kea Schwarz, RDN, LDN — Kea Schwarz Functional Nutrition, LLC
Work with me: dietitiankea.com • dietitiankea@gmail.com
Educational only; not a substitute for medical care.
