Tylenol 3 and Tylenol 4 contain the same two ingredients, acetaminophen and codeine, in the same size tablet. The only difference is the amount of codeine: Tylenol 3 has 30 mg of codeine, while Tylenol 4 has 60 mg, exactly double. Both contain 300 mg of acetaminophen.
What Each Tablet Contains
Both formulations pair a standard 300 mg dose of acetaminophen with codeine, an opioid pain reliever. The number after “Tylenol” tells you the codeine strength:
- Tylenol #3: 300 mg acetaminophen + 30 mg codeine
- Tylenol #4: 300 mg acetaminophen + 60 mg codeine
There is also a lesser-known Tylenol #2 (300 mg acetaminophen + 15 mg codeine). All three are Schedule III controlled substances under federal law, meaning they require a prescription and carry a moderate risk of dependence.
Why the Codeine Dose Matters
Codeine is a prodrug, which means it doesn’t relieve pain on its own. Your liver converts a small portion of each dose into morphine, and that morphine is what actually reduces pain. At 30 mg (Tylenol 3), this conversion produces enough morphine for mild to moderate pain. At 60 mg (Tylenol 4), the higher codeine dose generates more morphine, making it appropriate when a lower dose isn’t providing adequate relief.
However, there’s an important ceiling effect. FDA prescribing information notes that codeine doses above 60 mg do not provide additional pain relief but do increase the frequency of side effects. So Tylenol 4 essentially represents the upper useful limit of codeine in a single dose, not a midpoint on a larger scale.
Side Effects at Each Dose
Both products share the same side effect profile: constipation, nausea, drowsiness, dizziness, and lightheadedness. The difference is how often these occur. There is a direct relationship between the amount of codeine in your system and the likelihood of dose-related reactions like nausea, vomiting, and sedation. Moving from 30 mg to 60 mg roughly doubles your codeine exposure, so these effects become more common with Tylenol 4.
The more serious concern is respiratory depression, where breathing slows dangerously. This risk exists at any codeine dose but increases with higher amounts. It’s most likely during the first 24 to 72 hours of treatment or after a dose increase. For this reason, Tylenol 4 is typically reserved for people who have already tried a lower dose and found it insufficient.
How Your Genetics Affect Both
Because codeine relies on a specific liver enzyme to become morphine, your genetic makeup plays an outsized role in how well either product works for you. People fall into a few broad categories based on how active that enzyme is in their body.
If you’re a “poor metabolizer,” you convert very little codeine to morphine. Neither Tylenol 3 nor Tylenol 4 will provide much pain relief, regardless of the dose. An estimated 5 to 10% of people of European descent fall into this group, though it varies by population.
On the other end, “ultrarapid metabolizers” convert codeine to morphine faster and more completely than average. For these individuals, even a standard 30 mg dose can produce dangerously high morphine levels. Taking Tylenol 4 would amplify that risk considerably. This genetic variation is the reason the FDA added its strongest warning (a Boxed Warning) against giving codeine to children after tonsil or adenoid surgery, since it’s difficult to know which children metabolize the drug too quickly.
Acetaminophen Limits Apply to Both
Because both tablets contain the same 300 mg of acetaminophen, the daily acetaminophen ceiling is the real constraint on how many you can take. The maximum is 4,000 mg of acetaminophen per day from all sources combined. At 300 mg per tablet, that’s a hard cap of about 13 tablets, though prescribed doses are typically well below that. If you’re also taking other products that contain acetaminophen (cold medicines, headache tablets, sleep aids), those milligrams count toward the same limit. Exceeding it can cause liver damage severe enough to require a transplant.
This shared acetaminophen content is one reason the two formulations exist as separate products rather than simply telling patients to take two Tylenol 3 tablets. Two Tylenol 3 tablets would deliver 60 mg of codeine (matching Tylenol 4) but 600 mg of acetaminophen, double the per-dose amount. A single Tylenol 4 tablet delivers the same codeine with half the acetaminophen load.
When Each Is Typically Prescribed
Both are indicated for mild to moderately severe pain, with the choice between them based on how much relief a patient needs. Tylenol 3 is the more commonly prescribed starting point. It’s used for pain that over-the-counter options can’t handle but that doesn’t warrant a stronger opioid. Dental procedures, minor injuries, and certain chronic pain conditions are common scenarios.
Tylenol 4 is generally reserved for situations where 30 mg of codeine isn’t enough. Because codeine above 60 mg per dose doesn’t add benefit, Tylenol 4 also serves as a decision point: if it still isn’t controlling pain adequately, a different pain management approach is usually needed rather than simply more codeine.