Headache — what do you take? Menstrual cramps? Toothache? Standing in the pharmacy aisle, the choices look endless. But here's the thing: dozens of products, only a handful of actual ingredients. Learn the ingredients and choosing gets easy — and more importantly, you avoid the dangerous mistake of doubling up.
1. How do you choose. The shelf looks endless but pain relievers split into two families — NSAIDs for pain with swelling or inflammation (cramps, toothache, muscle pain), acetaminophen for plain headache or fever. That rule alone gets most cases right.
2. The most dangerous mistake. Doubling up. Cold and flu combinations already contain acetaminophen, so adding a headache tablet stacks it without you noticing — the FDA figures are 600 mg per dose and 4,000 mg a day, and an overdose damages the liver.
3. The reliable route. This is general information, not a diagnosis or prescription. The same symptom has different causes, and your conditions or medications can create risky combinations — asking a pharmacist is free, fast and the most reliable way to choose.
Know these two and you are halfway there
Over-the-counter pain relievers split into two families. They behave very differently.
| Acetaminophen | NSAIDs | |
|---|---|---|
| Common names | Tylenol (paracetamol) | Ibuprofen (Advil, Motrin), Naproxen (Aleve) |
| Reduces inflammation? | No | Yes — swelling, inflamed pain |
| Best for | Ordinary headache, fever, mild aches | Cramps, toothache, muscle/joint pain, sprains |
| Stomach | Gentler (OK on an empty stomach) | Can irritate → take with food |
| Main organ risk | Liver (overdose can be serious) | Stomach and kidneys |
The one-line rule. Inflammatory pain (cramps, toothache, muscle pain) → NSAIDs. Plain headache or fever → acetaminophen. That covers most situations.
What do you take for what
Headache
For an ordinary headache, try acetaminophen first. If it doesn't help, an NSAID is a reasonable next step.
- Some headache products contain caffeine (it boosts the effect — but can keep you up at night)
- Taking painkillers often and still getting headaches? The medication itself may be causing them (“medication-overuse headache”). See a doctor
Menstrual cramps
NSAIDs (ibuprofen, naproxen) work better here. Cramps are driven by prostaglandins — inflammatory compounds — and NSAIDs block them at the source. Acetaminophen doesn't.
- Timing matters — taking it as cramps begin, rather than after they peak, works notably better
- Take it with food if your stomach is sensitive
- If pain is severe, not controlled by OTC medicine, or getting worse over time → see a doctor (conditions like endometriosis can be the cause)
Toothache
Toothaches usually involve inflammation, so NSAIDs tend to work well. Dentists often recommend ibuprofen and acetaminophen together — they work through different pathways, so combining them is safe for short-term use and more effective than either alone.
Important. Painkillers mask the pain; they don't fix the cause. The decay or infection keeps progressing. See a dentist. Medication is only for getting through until then.
Cold and flu
Cold medicines are often multi-ingredient combination products — which is exactly where people get into trouble.
- Fever/aches — acetaminophen (in most combination cold products)
- Runny nose/sneezing — antihistamines (can cause drowsiness → don't drive)
- Congestion — decongestants like pseudoephedrine (can raise heart rate; caution with high blood pressure)
- Cough — cough suppressants / mucus — expectorants
Pick only what matches your symptoms. If you just have a runny nose, you don't need a product that also contains a cough suppressant.
The most dangerous mistake
Cold medicine + Tylenol = too much acetaminophen. Most combination cold products already contain acetaminophen. Adding Tylenol on top means taking a double dose of the same drug. Acetaminophen overdose can cause serious liver damage.
Always read the active ingredients on the package. Different brand names can contain the same drug.
- Acetaminophen — the maximum daily dose for healthy adults is commonly cited as 3,000–4,000mg, but guidance varies. Follow the label on your product.
- Never mix acetaminophen with alcohol — the liver risk rises sharply
- Don't take two different NSAIDs at once (ibuprofen + naproxen )
How much is too much — 600 and 4,000
Why doubling up is dangerous comes down to two numbers. Transcribed from the US Food and Drug Administration, checked 30 July 2026.
| Item | FDA source text |
|---|---|
| How many medicines contain it | “over 600 prescription and nonprescription medicines” contain acetaminophen |
| Daily maximum | “no more than 4,000 milligrams a day” |
| If you exceed it | “can cause serious liver damage” · “too much acetaminophen can lead to liver failure and death” |
| Alcohol | “talk to a health care professional if you drink three or more alcoholic drinks a day” |
| Where to look | the ingredients section of the Drug Facts label |
| Children | “never guess the dose.” If the label has no dose for your child's weight or age, ask a health care professional |
“Over 600” is the number that matters here. Counting the pain reliever bottle is not enough — cold and flu remedies and some prescription medicines carry the same ingredient.
How many tablets a day actually fit
| Situation | From cold medicine | Headroom left | Max 500mg tablets |
|---|---|---|---|
| Pain reliever alone | 0mg | 4,000mg | 8 |
| Cold medicine 325mg × 3 a day | 975mg | 3,025mg | 6 |
| Cold medicine 500mg × 3 a day | 1,500mg | 2,500mg | 5 |
Same pain reliever, but the ceiling moves from 8 tablets to 5 depending on what else you take (our calculation). Remember “8 is fine” and you will exceed the maximum on the day you catch a cold.
The assumption, stated plainly. Acetaminophen content in cold remedies varies by product. The 325mg and 500mg above are illustrative, and you have to read the Drug Facts on the product you actually take. We could not obtain agency data on the range of strengths sold in Korea.
Pain relievers split into two families
The FDA separates acetaminophen from NSAIDs. The NSAID ingredients named on the page are ibuprofen and naproxen.
| Item | Acetaminophen | NSAIDs (ibuprofen, naproxen) |
|---|---|---|
| What the FDA says it does | “temporarily relieves pain and temporarily reduces fever” | treated as a separate drug class |
| Main warning | liver damage and liver failure | — |
| Added 2024 | a rare serious skin reaction warning | referenced as the comparison in that context |
The page does not spell out the gastrointestinal bleeding or cardiovascular warnings for NSAIDs, so we did not transcribe them. They are widely known, but writing only what we verified is this blog's standard (see below).
When to ask first
- Are pregnant or breastfeeding (NSAIDs especially need caution)
- Have ulcers or stomach problems (NSAID caution)
- Have kidney or liver disease
- Have high blood pressure or heart disease
- Take other medications (especially blood thinners)
- Are giving medicine to a child — dosing depends on age and weight. Always confirm
When to stop self-treating
- Pain is not controlled by OTC medicine, or keeps getting worse
- You've been taking painkillers for the same problem for several days or more
- Sudden severe headache, or headache with fever, stiff neck, or confusion → seek care immediately
- A fever that lasts several days
- Rash, trouble breathing, or facial swelling after taking medicine → stop and get emergency care
Painkillers quiet the symptom — they don't fix the cause. If you need them for more than a few days, that's your signal to see a doctor.
Sources
- US Food and Drug Administration — agency source — “Don’t Overuse Acetaminophen” (checked 30 July 2026). Source for over 600 medicines containing it, the 4,000mg daily maximum, liver damage, the three-drinks-a-day advice, checking the Drug Facts ingredients section, and never guessing a child's dose.
- US Food and Drug Administration — agency source — “Acetaminophen” (checked 30 July 2026). Source for the split between acetaminophen and NSAIDs, the NSAID ingredients named (ibuprofen and naproxen), “liver failure and death,” and the rare serious skin reaction warning added in 2024.
- Our own calculation. 8 tablets alone, 6 alongside 325mg cold medicine, 5 alongside 500mg is 4,000mg less the cold-medicine share, divided by 500mg — not a table the FDA publishes.
Where to check further
- Korean standards and per-product content. Korea's drug safety pages would not open, so every figure here is US FDA data, and the 325 mg / 500 mg in the table are examples — Korea's drug information service lets you look up ingredients by product name, and the box itself is the most reliable source.
- NSAID gastrointestinal and cardiovascular warnings, and duration limits. Widely known, but not stated on the FDA page we opened, so not carried over — a pharmacist answers this against your own conditions.
- Whether 4,000 mg is your ceiling too. It can change with body weight, liver function and other medication, and the page gives no conditional values — with liver disease or regular drinking, get your own limit from a doctor.
As of July 2026. The figures and wording come from US FDA pages; the tablet arithmetic is ours. Choosing medicines at a US pharmacy is in our drugstore guide part 1 and part 2, travel supplies in the first aid kit article and the packing guide, and urgent care in the ER versus clinic article.
This article is general health information and does not replace medical diagnosis or prescription. Talk to a pharmacist or doctor when choosing a medicine or dose, and always read the label for directions and warnings.
