Hash and Kief

Quick answer

Hash and kief are two of the oldest and most commonly named cannabis concentrates. Both are built around the plant's sticky resin glands, called trichomes. This page covers vocabulary and evidence only. It does not describe how to make either product. For the gland itself, see trichomes and resin glands.

Evidence labels: insufficient evidence means studies are too few; marketing claim means the statement comes from sellers or glossaries rather than independent testing.

Kief

A provincial cannabis retailer's glossary describes kief (also called sift) as, basically, hash before it is pressed, a green powder. [1] A 2023 clinical framework paper described kief or dry sift as the collected gland heads from ground and sifted flower. [2] Because kief is a powder of plant gland material, its content depends on the flower it came from.

Hash and hashish

The same glossary says hash is made up of the plant's trichomes (kief) pressed into a ball or brick. [1] Bubble hash (also called ice water hash) appears as a separate category in the same clinical table. [2] Other names, such as "hashish," are used for the same family of products, and sources do not always agree on where one name ends and another begins.

How these differ from other concentrates

What is known about strength

Authors of a 2025 systematic review sorted potency studies into categories, including kief/resin at roughly 30 to 50% THC and concentrates at 60% or more, as comparison groups for the review (these are the authors' study categories, not guarantees about any product). [3] The 2023 clinical framework table listed higher ranges for kief and lower ones for bubble hash, which shows how much sources disagree. [2] Because ranges differ between sources and between batches, this site does not give a typical percentage. Composition varies, and verified batch data is not available here.

What research shows about health effects

• The 2025 review found only 42 eligible studies across all high-potency products, mostly on mental health and "problem" use, with "very low" certainty overall. [3] No study in that summary isolates hash or kief alone, so effects specific to them are insufficient evidence.
• Hash and kief are often smoked or vaporized. Smoking risks are covered on smoking and vaping cannabis risks.

Quality and labeling concerns

Hash is not automatically free of contaminants: the plant it comes from can carry pesticides, metals or microbes. See pesticides in cannabis products. A name like "pure" or "natural" is a marketing claim unless backed by a batch laboratory report.

Special groups

Pregnancy, breastfeeding, adolescence, heart and lung disease, and mental health conditions raise extra concerns for any high-THC product. See pregnancy and breastfeeding and psychosis and mania vulnerability.

Laws on hash differ by country and state and change. This is not legal advice; see cannabis laws by country.