Microcidal contains griseofulvin 125 mg, an oral antifungal. It treats fungal infections of the scalp, nails, skin, hair and beard that creams cannot reach. Courses are long — weeks for scalp, months for nails — and it must be taken with fatty food to be absorbed.
What is Microcidal?
Microcidal contains griseofulvin, an antifungal taken by mouth. It is a Schedule 4 prescription medicine.
Griseofulvin works quite differently from a cream. It is absorbed from the gut, carried in the bloodstream, and deposited in newly forming keratin — the protein that makes up skin, hair and nails. As new keratin grows in, it arrives already containing the antifungal, and the fungus cannot infect it. Griseofulvin then disrupts the fungal cell’s ability to divide.
That mechanism explains everything about how it is used. It does not kill the fungus in tissue already infected — it protects the new growth. The infected keratin has to grow out and be cut or shed away, and the treatment continues until it has.
That is why courses are so long, and why they are measured in the growth rate of the tissue:
- Scalp and skin: weeks to a few months.
- Fingernails: several months.
- Toenails: up to a year or more, since toenails grow slowly.
Stopping when it looks better is the commonest reason treatment fails — the visible improvement comes long before the infected keratin has fully grown out.
What is Microcidal commonly used for?
Griseofulvin treats dermatophyte (ringworm) infections that topical creams cannot reach:
- Scalp ringworm (tinea capitis) — its most important use, particularly in children. Scalp infections cannot be treated with cream, because the fungus lives inside the hair follicle below the surface.
- Fungal nail infection (onychomycosis), of fingernails and toenails.
- Beard infection (tinea barbae).
- Extensive or resistant ringworm of the body (tinea corporis).
- Athlete’s foot that has not cleared with topical treatment.
- Fungal infections of the palms and soles, where skin is thick.
Scalp ringworm deserves particular attention. It is common in South African children, causes scaly patches with hair loss and sometimes a boggy inflamed swelling (a kerion), and it will not respond to any cream — the medicine has to reach the follicle from within. Untreated, it can cause permanent scarring and hair loss.
It is also contagious, spreading through direct contact and shared combs, brushes, hats, pillows and clippers. Household members should be checked, and an antifungal shampoo is often used alongside to reduce spread — though the shampoo alone does not cure it.
Nail infections need confirming before a long course. Not every thickened, discoloured nail is fungal — psoriasis, trauma and other conditions look similar. A nail clipping sent for testing is worth doing before committing to many months of tablets.
How Microcidal fits into this medicine category
| Group | Examples | Reaches |
|---|---|---|
| Oral antifungals | Griseofulvin (Microcidal), terbinafine, fluconazole | Scalp, nails, hair, extensive skin infection |
| Topical antifungals | Clotrimazole (Canex T, Fungistop Topical) | Skin surface only |
| Vaginal antifungals | Clotrimazole (Canex V) | Vaginal thrush |
| Antifungal + steroid | Clomaderm | Inflamed fungal skin infection |
| Antibiotics | Amoxicillin | Bacterial infection — not fungal |
Terbinafine is now often preferred for nail infections, with shorter courses. Griseofulvin remains widely used for scalp ringworm in children, where it has the longest safety record. See the antibiotics and antimicrobials hub.
What to check before using Microcidal
Take it with a fatty meal. This is not optional advice — griseofulvin is poorly absorbed without fat, and taking it on an empty stomach can mean a months-long course simply does not work. Full-cream milk, yoghurt, peanut butter or a meal containing oil or butter all serve.
Complete the full course, however long, and however much better it looks.
Avoid alcohol. Griseofulvin can cause a flushing reaction with alcohol, and it increases its effects.
Use sun protection — griseofulvin causes photosensitivity.
Tell your prescriber or pharmacist if:
- You are pregnant, planning pregnancy or breastfeeding. Griseofulvin must not be used in pregnancy. Effective contraception is needed during treatment and for one month afterwards, and men are generally advised to avoid fathering a child for six months after the course.
- You take the contraceptive pill. Griseofulvin reduces its effectiveness — additional contraception is needed. This is easily missed and genuinely important.
- You have liver disease, or porphyria, in which it must not be used.
- You have lupus, which griseofulvin can worsen.
- You take warfarin — griseofulvin reduces its effect; or ciclosporin, or phenobarbital.
- The medicine is for a child — dosing is by weight, and a suspension is available.
Expect monitoring on prolonged courses — liver function and blood counts.
Follow the dispensing label. This page does not set doses.
Possible cautions and when to ask a pharmacist or doctor
Take it with fat, finish the course, and use contraception. Those three between them account for most treatment failures and most avoidable harm.
Headache, nausea and stomach upset are common early and usually settle.
Sun sensitivity is marked — use sunscreen and cover up.
A flushing reaction with alcohol is recognised; avoid alcohol during the course.
Liver effects are uncommon but reported. Report yellowing of the skin or eyes, dark urine, pale stools or persistent nausea.
Blood count effects with long courses — report a sore throat, fever, mouth ulcers or unusual bruising.
Treat the source and prevent reinfection. For scalp ringworm, check household members, do not share combs, brushes, hats or pillows, and wash bedding hot. For foot and nail infections, dry between the toes, alternate shoes, and treat athlete’s foot alongside — reinfection from untreated feet is a common reason nail treatment fails.
If there is no improvement after the expected period, go back rather than continuing. The diagnosis may need confirming, or a different antifungal may be needed.
Seek medical attention for yellowing of the skin or eyes, dark urine with pale stools, a rash that blisters or peels, a severe sunburn reaction, fever with a sore throat or mouth ulcers, unusual bruising or bleeding, or numbness and tingling in the hands or feet.
Related medicine guides
Frequently asked questions
What is Microcidal used for? Fungal infections of the scalp, nails, hair, beard and skin that creams cannot reach. It contains griseofulvin.
Why must I take it with fatty food? Griseofulvin is poorly absorbed without fat. Taking it on an empty stomach can mean the whole course fails.
Why is the course so long? It protects newly growing keratin rather than killing fungus in tissue already infected. Treatment continues until the infected hair, skin or nail has grown out — up to a year for toenails.
Why can a cream not treat scalp ringworm? The fungus lives inside the hair follicle, below the surface. A cream cannot reach it, so oral treatment is required.
Does it affect the contraceptive pill? Yes. Griseofulvin reduces its effectiveness, so additional contraception is needed during treatment.
Can I take it in pregnancy? No. It must not be used in pregnancy, and effective contraception is needed during treatment and for a month afterwards.