Oral vs Sublingual Marketing Claims

The claim

Many oil labels say to hold drops under the tongue for better or faster absorption. "Sublingual" means under the tongue; "oral" here means swallowed. This page checks what published studies show. It gives no amounts or instructions for use. Evidence labels used here: mixed, insufficient evidence, marketing claim and Proper evidence not found.

What the best-matched human trial found

A randomized, participant-blinded crossover study at Loughborough University gave eight healthy men hemp oil containing 69 mg/mL CBD, either as sublingual drops or inside gelatin capsules (a labeled study amount, not a recommendation). Blood CBD profiles did not differ: peak concentration (28.0 versus 24.0 ng/mL), time to peak (about 4 hours in both) and total exposure were comparable. [1] The authors concluded this implies that sublingual CBD oil is swallowed before oral mucosal absorption occurs. [1]

Reading it fairly. Eight men is a very small group, only one product was tested. One study cannot rule out differences for other formulations (for example sprays or tablets) or other people. It does, however, mean the claim "sublingual absorbs better" is not supported by this direct test.

What the broader review says

A 2024 review of CBD delivery found that transdermal and transmucosal routes deliver CBD into the body more slowly, and that some emulsion formulations deliver more rapidly. [2] It adds that evidence is limited on whether a change in blood pattern equals better therapeutic effect. [2] Several authors of that review work for companies in the cannabinoid and delivery business, which is worth knowing when weighing it.

Food changes absorption more than where the drops go

• In a 2025 crossover study, a high-fat meal significantly raised the bioavailability of CBD from a hemp extract compared with fasting; the peak was about 17 times higher (geometric mean ratio 17.4) in 11 healthy adults. [3]
• In healthy adults given the approved CBD medicine as a single large study amount, a high-fat meal raised total exposure about 3.8-fold versus fasting, a low-fat meal 2.7-fold and whole milk 2.4-fold; variability between and within people was moderate to high. [4]

These are findings about blood levels in studies, not advice on how to take anything.

Blood levels are not benefit

Faster or higher blood levels do not prove a better outcome for symptoms or conditions. The review above states that limit directly. [2] Label: insufficient evidence that sublingual use gives a clinical advantage; the claim is a marketing claim.

What about THC products

NIDA describes tinctures as consumed under the tongue or added to foods or drinks and says they can deliver large amounts of THC. [5] I found no study in the sources read that directly compared swallowed and sublingual THC oils, so no claim is made. Proper evidence not found.

Safety

Whatever the route, the same cautions apply: possible liver effects and drug interactions with CBD [6], and products kept out of reach of children. See what is CBD oil and tinctures and carrier oils. For the approved medicine, see approved cannabinoid medicines.