This article provides general information only and doesn't replace speaking with a medical professional. If you're reading this after a check-in email from your clinician or the Medical Support team, please don't click "Yes" to "Does this article answer your question?" That stops us from seeing your enquiry.
No treatment is without the possibility of side effects. They can develop when you start a new treatment, after taking it for a while, or if you change your dose or suddenly stop. Side effects aren't always serious, and not everyone experiences them.
To read about side effects specific to your treatment plan, visit the "Help" section in your patient profile, or visit our support centre. If side effects worry you at any point, contact our Medical Support Team here.
Common side effects by treatment
Weight loss. Because weight loss treatment slows gastric emptying, it can cause side effects like reflux, constipation, vomiting, nausea, and fatigue, especially early on. See the symptom guides below for how to manage each.
PE. May cause tiredness, nausea, headaches, drowsiness, stomach discomfort, or difficulty concentrating.
ED. ED treatments work by widening blood vessels and increasing blood flow to the penis when stimulated, which can also affect blood flow elsewhere in the body. Common side effects include headaches, nasal congestion, back or muscle aches, facial flushing, and stomach discomfort. These usually subside as treatment wears off. ED treatments only help you maintain an erection when there's sexual stimulation, and won't cause an erection without it.
Hair. Hair loss treatments work by inhibiting the enzyme responsible for hair loss and increasing blood flow to the scalp, which can cause changes in sexual desire or performance, dizziness, lightheadedness, local irritation, or itchy skin. It's also common to see temporary "shedding" in the first 3 to 6 months, as weaker hairs are pushed out to make way for thicker, fuller ones. This is a sign your treatment is working, and it should subside over time. Read our Guide to hair loss to learn more.
Acne. Tingling, stinging, redness, peeling, irritation, purging, and increased sensitivity to sunlight are all common when starting a topical treatment. Purging (a short-term increase in acne as your skin clears out deep-forming lesions) can last 4 to 16 weeks. A small number of patients experience less common effects like perioral or irritant contact dermatitis, which may need a GP assessment. Some tips to help:
- Use the "sandwich technique": apply a moisturiser 10 minutes before and after your formula.
- Introduce your formula slowly, starting with a thin layer every 3 to 4 days, and back off to every 7 days if your skin is irritated.
- Try "short-contact" therapy: apply at night and wash off with a gentle cleanser after an hour.
- Avoid your nose, eyes, and mouth, and use a barrier ointment like Vaseline in sensitive areas.
- Apply SPF 50+ or avoid direct sun exposure, and apply retinoids at night to reduce sun sensitivity.
- Nourish your skin barrier with a healing cream, and avoid adding other active ingredients while you're getting started.
Sleep. May cause drowsiness, headaches, dizziness, and unusual dreams. Stay well hydrated, avoid alcohol and other sedatives with your treatment, avoid driving when drowsy, and only take your treatment if you have 7 hours to sleep. These treatments aren't associated with withdrawal or dependence, so you can stop at any time, and they won't cause rebound insomnia.
Managing common symptoms
Nausea. Eat three small meals a day plus one to two snacks to keep your stomach from being empty. Choose bland, cold foods like bananas, custard, jelly, tinned fruit, crackers, and toast. Ginger or peppermint tea can help soothe symptoms, and staying hydrated (at least 2 litres a day) also helps minimise headaches and constipation.
Vomiting. Drink small amounts of fluid frequently — try ginger ale, clear juice, soda water, or oral rehydration solutions, or suck on ice blocks. Once vomiting subsides, ease back into eating with bland, low-fat foods before returning to a normal diet.
Constipation. Drink at least 2 litres of fluid a day, gradually increase fibre-rich foods (fruits, vegetables, whole grains, legumes, nuts, seeds), and stay physically active to support regular bowel movements.
Diarrhoea. Stay hydrated with small, frequent sips of fluid. Temporarily avoid fruits, lactose, vegetables, and natural juices, and opt for easily digestible foods like dry toast, crackers, white rice, bananas, and potatoes.
Fatigue. Maintain a balanced diet of three small meals and one to two snacks a day, stay hydrated (2 to 3 litres daily), and build short bursts of activity like walking into your day.
Headaches. Stay hydrated (over 2 litres a day), try relaxation techniques like deep breathing, yoga, or meditation, and identify and cut back on triggers like caffeine, alcohol, or chocolate.
Dizziness. Keep your fluid and food intake up throughout the day to avoid drops in blood sugar. If you feel dizzy or faint, lie down until it passes, then stand up carefully.
Insomnia. Avoid nicotine and alcohol before bed, limit caffeine after midday, get daytime exercise (but not right before bed), and limit screen time, especially in the 30 minutes before bed.
Injection site reactions. Usually mild — slight redness or itchiness that comes and goes. Try a cold compress or ice pack (with a cloth barrier, 20 minutes max), gentle fragrance-free bath products, or an over-the-counter antihistamine or anti-itch cream from your pharmacist. To help prevent irritation: ice the site 15 minutes before injecting, rotate between injection sites (like abdomen and thigh), and let refrigerated treatment warm up for 30 minutes before injecting. If your symptoms don't subside or you're concerned, message our Medical Support Team here.
Checking other medications and supplements
Most treatments come with a sheet explaining what they are and how to take them safely, but this won't list every possible interaction. Tell your clinician about all your treatments at Hims so they can check for interactions before giving you a new one, and avoid combining treatments until this has been checked. If you're unsure whether a treatment, supplement, or herbal remedy you take can interact with your treatment plan, message our Medical Support Team here.
Allergic reactions
Drug allergies range from minor irritations to life-threatening emergencies. Anaphylaxis can show up within minutes, or even hours, after exposure to an allergen in your treatment.
Anaphylaxis is a life-threatening emergency. Stop your treatment and call 000 immediately if you experience: difficulty breathing, swelling of the tongue, lips, or throat, facial swelling, severe skin reactions, vomiting, abdominal pain, a weak and rapid pulse, chest pain, rapidly worsening symptoms, confusion, sudden voice hoarseness or inability to speak, changes in vision, dizziness, or fainting.
For milder reactions, like skin rashes or hives, stop your treatment and see your local GP or Emergency Department, since these can be hard to assess online. Once you're safe, update your clinician and our Medical Support Team here about the incident, and send a photo of the batch number.
Changes to mood or mental health
Changes in mood or mental health can come from many factors, and it's important to get the right support. If you're experiencing changes to your mood, hold off on further doses of your treatment and reach out to our Medical Support team here.
If you need immediate attention for your mental health, contact Beyond Blue on 1300 22 4636 or Lifeline on 13 11 14. If your life is in danger, call 000.
A good first step is talking to someone you trust, like a partner, family member, friend, or colleague. We also encourage you to seek professional support from your GP, a psychologist, or a counsellor for a face-to-face assessment — Health Direct Service Finder can help you find one nearby.
Other resources to try:
Head to Health for advice, assessment, and referral into local mental health services. Call 1800 595 212, 8:30am to 5pm weekdays (excluding public holidays). Butterfly Foundation for people affected by eating disorders and negative body image, and their family and friends. Call 1800 33 4673 or chat online.
When to seek emergency care
Call 000 or visit your nearest Emergency Department immediately if you experience:
- Severe abdominal pain, chest pain, breathing difficulties, wheezing, or swelling in a limb, face, lips, tongue, or throat
- A prolonged, painful erection lasting longer than 4 hours (ED treatments)
- Circulation issues, a weak or rapid pulse, an irregular heartbeat, or a prolonged increased heart rate
- Severe mood changes, confusion, suicidal thoughts, or loss of consciousness
- Sudden changes in vision, hearing loss, dizziness, or fainting
- Numbness, slurred speech, or other neurological symptoms
- A severe or sudden headache, especially one that wakes you at night or feels like a thunderclap
- Vomiting blood or material resembling coffee grounds, green vomit, or bile-coloured vomit * Blood or pus in your stool, or bloody diarrhoea lasting more than 72 hours
- A fever over 38.5°C, chronic fever, or night sweats with swollen lymph nodes
- Signs of dehydration, or persistent vomiting lasting more than 48 hours
- Severe or worsening skin reactions, blistering, or oozing at an injection site
If you're unsure and want urgent medical advice, call Health Direct on 1800 022 222 to speak with a registered nurse.