Blister packaging is a pre-formed plastic or aluminum shell with individual pockets (called cavities or blisters) that hold a product, sealed with a flat backing of foil, film, or cardboard. You’ve almost certainly used one: the foil-backed strip you push a pill through, the clear plastic holding batteries at the store, or the sealed tray around a USB drive. It’s one of the most common packaging formats in pharmaceuticals, consumer electronics, and retail goods.
How a Blister Pack Is Built
Every blister pack has four functional layers. The forming film is the material shaped into pockets that cradle each item. The lidding is the flat layer sealed over the top to enclose everything. Between them sits a heat-seal coating that bonds the two layers together. Finally, printed information (dosage instructions, branding, lot numbers) is applied to the lidding or a surrounding card.
The forming film can be made from several plastics depending on what’s being packaged. PVC is the most economical and widely used option. It’s transparent and easy to shape, but on its own it offers limited protection against moisture and oxygen. Coating PVC with a second plastic called PVDC improves moisture resistance by 5 to 10 times, making it a popular middle-ground choice for medications in humid climates. For drugs that are especially sensitive to moisture or oxygen, a high-performance film called Aclar (made from PCTFE) provides the strongest barrier available in a clear blister material.
On the lidding side, aluminum foil dominates. It blocks moisture, oxygen, and UV light more effectively than any polymer film. Soft-tempered foil, roughly 1.0 mil thick (one-thousandth of an inch), is flexible enough for child-resistant designs where you need to peel or bend the lid. Hard-tempered foil, slightly thinner at about 0.8 mils, tears cleanly when you push a tablet through, which is why it’s the standard for push-through pill packs. Other lidding options include PET film, paper laminates, and multi-layer composites, though these are less common in pharmaceutical use.
Thermoforming vs. Cold Forming
There are two main ways to manufacture blister packs, and the choice between them comes down to what the product needs.
Thermoforming uses heat. A clear PVC sheet is warmed between heating plates until it becomes soft and pliable, then pressed or stamped into a mold to create the pocket shapes. Because PVC is transparent, the finished pack lets you see the product inside. This method is faster and cheaper, making it the default for most over-the-counter medications and consumer goods. The tradeoff is that clear plastic lets light through, so thermoformed packs aren’t suitable for light-sensitive drugs.
Cold forming skips the heat entirely. Instead, an aluminum-based laminate is mechanically stamped into a mold at room temperature. The aluminum stretches and holds the pocket shape once the stamp is removed. Because the entire pack is wrapped in aluminum (both the cavity and the lid), cold-formed blisters provide a near-complete barrier against moisture, oxygen, and light. This makes them the go-to choice for sensitive pharmaceuticals. The downside: cold forming costs more and produces larger packs because aluminum doesn’t stretch as tightly around each cavity as heated plastic does.
Regardless of method, the remaining steps are the same. Products are placed into the formed cavities, a sheet of lidding material is heat-sealed over the top, and a precision die cutter separates the finished packs and adds perforations so individual doses can be torn apart.
Why Pharmaceuticals Rely on Blister Packs
The biggest advantage of blister packaging for medications is that each dose sits in its own sealed compartment. Opening one pocket doesn’t expose the rest of the supply to air or moisture, which is a significant problem with traditional pill bottles where every dose gets a burst of humid air each time you open the cap. This individual sealing also means each cavity has to be visibly ripped or broken to access the product, creating built-in tamper evidence. If a pocket has been opened, you can see it immediately.
Blister packs also improve how consistently people take their medications. An analysis published in The American Journal of Managed Care found that patients using blister-style compliance packaging achieved an average adherence rate of 71%, compared to 63% for patients using traditional bottles. That 8-percentage-point gap matters for people managing chronic conditions where missed doses can lead to hospitalizations. The visual layout of a blister card, with each day or dose clearly marked, gives patients an at-a-glance record of whether they’ve taken today’s pill.
Child-Resistant Designs
Standard push-through blister packs are easy enough for an adult but can also be easy for a child. For medications that require child-resistant packaging, manufacturers use modified designs. One common approach is the “bend, peel back, push out” system: you have to fold the blister card at a specific angle, peel back a layer, and then push the tablet through. This sequence of steps is simple for an adult following instructions but difficult for a young child to figure out. These designs are formally classified and tested against safety standards set by the Consumer Product Safety Commission.
Beyond Pharmaceuticals
While the pharmaceutical industry is the largest user of blister packaging, the format shows up everywhere. Retail products like batteries, small electronics, toys, and hardware are commonly sold in clamshell blisters, a variation where two formed plastic halves are sealed together or a single blister is mounted on a printed card. These serve a different purpose: visibility and theft deterrence. The clear plastic lets shoppers see exactly what they’re buying while making the product difficult to pocket without the bulky packaging.
Food-grade blister packs are used for individual servings of candy, gum, and single-use condiment pods. In these applications, the barrier properties of the forming film and lid are tuned for freshness rather than pharmaceutical stability, but the basic structure is identical.
Environmental Challenges and New Materials
Traditional blister packs are difficult to recycle. A typical pharmaceutical blister combines PVC plastic with aluminum foil, bonded by a heat-seal adhesive. Most municipal recycling programs can’t separate these layers, so the packs end up in landfills. PVC in particular is one of the least recyclable common plastics.
The industry is actively working on alternatives. Companies like TOPPAN and IWK Packaging Systems are developing aluminum-free and mono-material blister designs that use a single type of recyclable material for the entire pack. IWK has introduced a machine to the North American market that produces fully cardboard blisters, replacing both the plastic cavity and the backing card with paper-based materials. Other manufacturers are experimenting with lamination-based approaches that avoid the multi-plastic co-extrusions that make recycling so difficult. These designs are still gaining traction, but they represent a meaningful shift toward packaging that can actually enter a recycling stream after use.