Medicines
Medicines are chemical substances used to treat, control or prevent illness. Common groups include:
- Analgesics (painkillers) relieve pain. Aspirin and paracetamol ease mild pain and fever; codeine relieves stronger pain.
- Antibiotics kill or stop the growth of bacteria. Penicillin is a well-known example; they do not work on viruses.
- Psychotherapeutic medicines act on the mind: stimulants, antidepressants and antipsychotics.
Traditional medicines use natural plant materials (herbs), such as ginger and tongkat ali. Every medicine must be taken at the correct dose: too little may not work, while too much can be toxic. Misusing medicines — for example taking someone else stimulant tablets — is dangerous and can lead to drug dependence.
Key idea
Match the medicine to its job: analgesic → relieves pain; antibiotic → kills bacteria (not viruses); antidepressant → treats depression. Always follow the correct dose.
Cosmetics
Cosmetics are substances applied to the body to clean, protect or beautify it. Main groups are skincare (moisturiser, sunscreen), haircare (shampoo, hair dye), decorative (lipstick, foundation) and perfume. Cosmetics contain a base (water, oil or wax) plus active chemicals, colours and fragrance. Some of these chemicals can trigger allergy or skin irritation, so a patch test and reading the ingredient list are wise.
| Cosmetic | Example chemical / role |
|---|---|
| Sunscreen | Titanium dioxide, blocks UV |
| Lipstick | Wax and pigment for colour |
| Deodorant | Aluminium compound, controls sweat smell |
Worked example
Why can antibiotics not cure the common cold? The cold is caused by a virus, but antibiotics only kill bacteria. Taking antibiotics needlessly can lead to resistant bacteria.
Remember
- Overuse of antibiotics causes resistance.
- Some cosmetic chemicals cause allergy or skin irritation.
- Illegal whitening agents may contain toxic mercury or hydroquinone.